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Curiosity Textbook of Science for Grade 6 0 Prelims.indd 1 10-07-2024 18:12:40  0677 – Curiosity ISBN 978-93-5292-972-6 Textbook of S...

Curiosity Textbook of Science for Grade 6 0 Prelims.indd 1 10-07-2024 18:12:40  0677 – Curiosity ISBN 978-93-5292-972-6 Textbook of Science for Grade 6 First Edition ALL RIGHTS RESERVED July 2024 Jyeshtha 1946  No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise without the prior permission of the publisher. PD 700T BS  This book is sold subject to the condition that it shall not, by way of trade, be lent, re-sold, hired out or otherwise disposed of without the publisher’s consent, in any form of binding or © National Council of Educational cover other than that in which it is published. Research and Training, 2024  The correct price of this publication is the price printed on this page, Any revised price indicated by a rubber stamp or by a sticker or by any other means is incorrect and should be unacceptable. 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Offset (P) Ltd., 10, Sports Complex Enclave, Delhi Road, Fajruddin Meerut 250 002 Junaid Digital Arts 0 Prelims.indd 2 15-07-2024 14:51:19  Foreword The National Education Policy 2020, envisages a system of education in the country that is rooted in Indian ethos and its civilisational accomplishments in all domains of human endeavour and knowledge while at the same time preparing the students to constructively engage with the prospects and challenges of the twenty-first century. The basis for this aspirational vision has been well laid out by the National Curriculum Framework for School Education (NCF-SE) 2023 across curricular areas at all stages. Having nurtured the students’ inherent abilities touching upon all the five planes of human existence, the pañchakośhas, in the Foundational and the Preparatory Stages have paved the way for the progression of their learning further at the Middle Stage. Thus, the Middle Stage acts as a bridge between the Preparatory and the Secondary Stages, spanning three years from Grades 6 to 8. This framework, at the Middle Stage, aims to equip students with the skills that are needed to grow, as they advance in their lives. It endeavours to enhance their analytical, descriptive, and narrative capabilities, and to prepare them for the challenges and opportunities that await them. A diverse curriculum, covering nine subjects ranging from three languages—including at least two languages native to India—to Science, Mathematics, Social Sciences, Art Education, Physical Education and Well-being, and Vocational Education promotes their holistic development. Such a transformative learning culture requires certain essential conditions. One of them is to have appropriate textbooks in different curricular areas as these textbooks will play a central role in mediating between content and pedagogy—a role that will strike a judicious balance between direct instruction and opportunities for exploration and inquiry. Among the other conditions, classroom arrangement and teacher preparation are crucial to establish conceptual connections both within and across curricular areas. The National Council of Educational Research and Training, on its part, is committed to providing students with such high-quality textbooks. Various Curricular Area Groups, which have been constituted for this purpose, comprising notable subject-experts, pedagogues, and practising teachers as their members, have made 0 Prelims.indd 3 10-07-2024 18:12:41  all possible efforts to develop such textbooks. Curiosity, Textbook of Science for Grade 6, is one of these. It has been developed in consonance with the recommendations of NEP 2020 and the NCF-SE 2023 to take students on a journey of experiential learning by citing examples from the world of the learners. The content stimulates curiosity, a sense of exploration, questioning, and critical thinking. The content seamlessly weaves together concepts from physics, chemistry, biology, and earth science, along with cross-cutting themes like environmental education, value education, inclusive education, and Indian Knowledge Systems (IKS). The textbook aims to engage learners through an integrated approach by including multiple activities and thoughtful use of technology. The textbook offers ample opportunities for reflection and group discussions. To encourage creativity and innovation, it is feasible to regard students as active participants in the learning process, rather than mere recipients of a predetermined set of knowledge. This can only be achieved if the necessary number of hours are dedicated to science teaching–learning annually as outlined in NCF-SE 2023. The pedagogical approach of the textbook also considers how important it is for students to think critically, reason well and make decisions. It also provides students with numerous opportunities to learn from each other, making the learning experience more engaging for both teachers and students. However, in addition to this textbook, students at this stage should also be encouraged to explore various other learning resources. School libraries play a crucial role in making such resources available. Besides, the role of parents and teachers will also be invaluable in guiding and encouraging students to do so. With this, I express my gratitude to all those who have been involved in the development of this textbook and hope that it will meet the expectations of all stakeholders. At the same time, I also invite suggestions and feedback from all its users for further improvement in the coming years. Dinesh Prasad Saklani Director New Delhi National Council of Educational 30 June 2024 Research and Training iv 0 Prelims.indd 4 10-07-2024 18:12:42  About the Book Curiosity, Textbook of Science for Grade 6 learners has been crafted in alignment with the recommendations of the National Education Policy (NEP) 2020 and the National Curriculum Framework for School Education (NCF-SE) 2023. The policy advocates a radical shift from a content-based education to a competency-based education, particularly in the realm of science. Therefore, the formulation of curricular goals for Science, subsequent competencies and learning outcomes are tailored towards competency-based learning. These curricular goals encompass various scientific concepts, including matter, the physical and living world, health, hygiene, and the exploration of the interface between science, society and technology. Additionally, the goals focus on the nature of science, its processes, historical and contemporary aspects of the development of science and science communication. While these goals are explicitly articulated, they are interdependent and collectively contribute to a better understanding of the world around us. Accordingly, the chapters of this textbook are structured around creative activities, reflective questions, processes and illustrations. The integration of the concepts from biology, chemistry, physics and earth science, and cross-cutting themes, such as value education, inclusive education, Indian Knowledge Systems (IKS) and environmental education have been interwoven in the content. Thus, the textbook aims to provide experience-based learning, rather than simply reading and memorising the concepts. In the Middle Stage, science teaching–learning adopts an integrated approach. This integrated approach develops fundamental capacities across biology, chemistry, physics and earth science. The use of an integrated approach helps the learners to appreciate the interrelations between subjects and make sense of their observations and experiences. Curiosity, Textbook of Science for Grade 6, comprises twelve chapters. As the name of the textbook suggests, there are numerous opportunities for the learners to explore the world of science and its nature. Through the chapters, learners will embark on a journey that will connect them to the world around and spark curiosity for further exploration. The hands-on activities embedded within each chapter engages the learners and provide them an opportunity to 0 Prelims.indd 5 10-07-2024 18:12:42  reflect on learning. These activities are inclusive in nature. Some activities require both the teacher and learners to prepare in advance. Chapter 1, titled ‘The Wonderful World of Science’, provides a holistic view of the new topic of Science introduced in the Middle Stage. It showcases, through examples, the essence of Science—a way of thinking, observing, and finding out by doing, and by asking questions. This chapter weaves together the concepts covered in the rest of the book, and aims to excite the readers as they start their adventures into the world of science. There are no assessment exercises in this chapter and is designed to be non-evaluative. Also, every chapter in the book begins with an introduction that makes the learners curious and tries to show different ways with which the goals of the curriculum can be achieved effectively. The chapters begin with the stories related to real-life situations, these are meant to capture learners’ interest and connect them with what is already known. The various activities given are based on scientific processes, designed to provide hands and minds-on experiences. Following each activity, there are questions to help learners understand and assess how well they have grasped the information. Questions are significant in the learning process. They help learners to explore and reinforce their understanding. One will also find many thought-provoking questions designed to encourage deep thinking, self-awareness and critical analysis. These questions prompt learners to ponder and delve deeper into their thoughts. In order to sustain the interest of the readers, some of the challenging ideas, additional information, poems, stories, strange facts and other interesting materials are also presented as add on non-evaluative content in the boxes labelled ‘Do you know?’, ‘More to know!’, ‘Think it over!’ and ‘More to do!’. The thrill of scientific inquiry comes from pursuing the unknown, giving learners the opportunity to think and explore beyond the syllabus. Some chapters also include a section called ‘Know a scientist’, which presents the contributions of Indian scientists related to that concept. All these box items, including brief biographies of scientists, are non-evaluative. The important ideas and steps in understanding a given concept of science are included as ‘Keywords’ at the end of each chapter. These ‘Keywords’ will help learners to acknowledge various vi 0 Prelims.indd 6 10-07-2024 18:12:42  ideas and encourage them to think more deeply about the content. The keywords related to scientific processes depict the steps or procedure involved in the scientific activities. These words guide learners on how scientific knowledge is generated, tested and applied. ‘Summary’ offers an overview of the chapter’s main points, reinforcing the key ideas discussed. It serves to outline the content presented in the chapter. A non-evaluative interesting element that has been incorporated in some of the chapters is the introduction of certain verses from various Indian texts to promote rootedness in the learners as envisaged in NEP 2020. The primary aim of Curiosity is to prepare the children for becoming the responsible members of the society, and therefore efforts have been made to raise awareness about various issues, such as gender, region, environment, health and hygiene, water scarcity and energy conservation. Activities given in the book endeavour to promote peer-learning and group activities. The assessment exercises, ‘Let us enhance our learning’, play a vital role in the learning process. They help to reinforce the understanding and identify areas for improvement, making them essential components of effective teaching and learning. Assessment consists of various exercises, from pictorial questions to creating puzzles and multiple-choice questions, to create a challenging and interesting experience for the learners. These questions also facilitate the evaluation of various competencies expected to be developed through a particular chapter. Peer and group activities to explore answers to the questions are also encouraged. A significant feature of the book is what we termed as ‘Learning further’. In this section, some projects and activities are designed to increase learners’ interaction with experts, teachers, parents and the wider community. Learners are encouraged to gather diverse information and draw their own conclusions. The textbook is just one way to learn. Learners should enhance their knowledge by exploring and observing their surroundings. Information and Communication Technology (ICT) can also be a valuable tool for learners’ learning and development, when used appropriately. Learners can explore ICT with the help of Quick Response (QR) codes provided in the textbook. QR codes make the reading experiences more interactive and enjoyable. These QR vii 0 Prelims.indd 7 10-07-2024 18:12:44  codes that have additional resources can be accessed by the learners at their own convenience and pace. These additional resources include videos, puzzles, games, quizzes, audio, documentaries and additional content on some topics. At the end of this book, learners will find a page titled ‘It is not the end, my friend!’. This includes words of encouragement, motivating learners to continue their educational journey and ignite their curiosity for further learning. It is meant to be non-evaluative. May the journey of every learner be filled with joy and continue the curiosity in the higher grades as well! We express our gratitude to all the members of the textbook development committee for their contributions in shaping this textbook. We look forward to the feedback of the readers. Anjni Koul Professor, Academic Convener Department of Education in Science and Mathematics NCERT viii 0 Prelims.indd 8 10-07-2024 18:12:44  National Syllabus and Teaching Learning Material Committee (NSTC) 1. M.C. Pant, Chancellor, National Institute of Educational Planning and Administration (NIEPA), (Chairperson) 2. Manjul Bhargava, Professor, Princeton University (Co-Chairperson) 3. Sudha Murty, Acclaimed Writer and Educationist 4. Bibek Debroy, Chairperson, Economic Advisory Council–Prime Minister (EAC–PM) 5. Shekhar Mande, Former Director General, CSIR, Distinguished Professor, Savitribai Phule Pune University, Pune 6. Sujatha Ramdorai, Professor, University of British Columbia, Canada 7. Shankar Mahadevan, Music Maestro, Mumbai 8. U. Vimal Kumar, Director, Prakash Padukone Badminton Academy, Bengaluru 9. Michel Danino, Visiting Professor, IIT–Gandhinagar 10. Surina Rajan, IAS (Retd.), Haryana, Former Director General, HIPA 11. Chamu Krishna Shastri, Chairperson, Bhasha Samiti, Ministry of Education 12. Sanjeev Sanyal, Member, Economic Advisory Council–Prime Minister (EAC–PM) 13. M.D. Srinivas, Chairperson, Centre for Policy Studies, Chennai 14. Gajanan Londhe, Head, Programme Office, NSTC 15. Rabin Chhetri, Director, SCERT, Sikkim 16. Pratyusha Kumar Mandal, Professor, Department of Education in Social Science, NCERT, New Delhi 17. Dinesh Kumar, Professor and Head, Planning and Monitoring Division, NCERT, New Delhi 18. Kirti Kapur, Professor, Department of Education in Languages, NCERT, New Delhi 19. Ranjana Arora, Professor and Head, Department of Curriculum Studies and Development, NCERT (Member-Secretary) 0 Prelims.indd 9 10-07-2024 18:12:44 0 Prelims.indd 10 10-07-2024 18:12:44  Textbook Development Team Chairperson, Curricular Area Group (Science) Shekhar C. Mande, FNA, FASc, FNASc, Former Director General, CSIR, Distinguished Professor, Bioinformatics Centre, Savitribai Phule Pune University, Honorary Distinguished Scientist, National Centre for Cell Science, Pune. Contributors Arnab Bhattacharya, Centre Director, Homi Bhabha Centre for Science Education, Tata Institute of Fundamental Research (TIFR), Mumbai, Professor, Department of Condensed Matter Physics and Material Science, TIFR, Mumbai (Chairperson, Physics Sub-group) Ashish Kumar Srivastava, Assistant Professor, Department of Education in Science and Mathematics, NCERT, New Delhi Gagan Gupta, Associate Professor, Department of Education in Science and Mathematics, NCERT, New Delhi Meher Wan, Scientist, CSIR-National Institute of Science Communica- tion and Policy Research, New Delhi M. S. Sriram, Former Professor and Head, Department of Theoretical Physics, University of Madras, Chennai and President, K. V. Sarma Research Foundation, Chennai Ritika Anand, Principal, St. Mark’s Senior Secondary Public School, Meera Bagh, New Delhi Sarita Vig, Professor, Indian Institute of Space Science and Technology (IIST), Thiruvananthapuram V. B. Bhatia, Former Professor, Department of Physics and Astrophysics, University of Delhi, Delhi Rachna Garg, Professor, Department of Education in Science and Mathematics, NCERT, New Delhi (Coordinator, Physics Sub-group) R. Shankar, Adviser, International Geoscience Education Organisation, Coordinator, International Earth Science Olympiad and Former Professor, Mangalore University, Mangaluru (Chairperson, Earth Science Sub-group) Abhay Kumar, Assistant Professor, Central Institute of Educational Technology, NCERT, New Delhi 0 Prelims.indd 11 10-07-2024 18:12:44  H. L. Satheesh, Principal, Maharshi Public School, Mysuru Poonam Katyal, Former TGT, Zeenat Mahal Sarvodaya Kanya Vidyalaya, Jafrabad, Delhi R. Srinivasan, Visiting Professor, Divecha Centre for Climate Change, Indian Institute of Science, Bengaluru T. A. Viswanath, Former Associate Professor, Goa University, Goa R. R. Koireng, Associate Professor, Department of Curriculum Studies and Development, NCERT, New Delhi (Coordinator, Earth Science Sub-group) Saroj Ghaskadbi, Former Senior Professor, Savitribai Phule Pune University, Pune (Chairperson, Biology Sub-group) C. V. Shimray, Associate Professor, Department of Education in Science and Mathematics, NCERT, New Delhi Dinesh Kumar, Professor and Head, Planning and Monitoring Division, NCERT, New Delhi Karthick Balsubramanian, Scientist F, Agharkar Research Institute, Pune K. V. Sridevi, Associate Professor, Regional Institute of Education, NCERT, Ajmer Pankaj Jain, Director, Academic and Operations, Seed2Sapling Education Foundation, Bengaluru Pooja Gokhle, Assistant Professor, Sri Venkateshwara College, University of Delhi, New Delhi Preeti Khanna, Rehabilitation Professional (Visual Impairement), National Association for The Blind, New Delhi Pushplata Verma, Associate Professor, Department of Education in Science and Mathematics, NCERT, New Delhi Sarita Kumar, Professor, Acharya Narendra Dev College, University of Delhi, Delhi Somdutta Karak, Science Communications and Outreach Officer, CSIR-Center for Cellular and Molecular Biology, Council for Scientific and Industrial Research, Hyderabad Sujata Bhargava, Former Professor, Savitribai Phule Pune University, Pune Yukti Sharma, Professor, Department of Education (CIE), University of Delhi, Delhi xii 0 Prelims.indd 12 10-07-2024 18:12:44  Sunita Farkya, Professor and Head, Department of Education in Science and Mathematics, NCERT, New Delhi (Coordinator, Biology Sub-group) Uday Maitra, Honorary Professor and INSA Senior Scientist, Indian Institute of Science, Bengaluru (Chairperson, Chemistry Sub-group) Anand Arya, Associate Professor, Regional Institute of Education, NCERT, Ajmer Jaya P. Swaminathan, Teacher Developer, Royal Society of Chemistry, Bengaluru Padma Prabhu, Former TGT, Kendriya Vidyalaya Sangathan and Teacher Developer, Royal Society of Chemistry, Bengaluru Pramila Tanwar, Associate Professor, Department of Education in Science and Mathematics, NCERT, New Delhi Ravindra Kumar Parashar, Professor, Department of Education in Science and Mathematics, NCERT, New Delhi Ravijot Sandhu, PGT (Chemistry), Navyug School, Laxmibai Nagar, New Delhi Ruchi Verma, Professor, Department of Education in Science and Mathematics, NCERT, New Delhi Sandhiya Lakshmanan, Scientist, CSIR-National Institute of Science Communication and Policy Research, New Delhi Sekar Venkatraman, Head of Department, Isha Home School, Coimbatore Sunita Malhotra, Professor, Indira Gandhi National Open University, New Delhi Tarun Choubisa, Director, Pedagogy and Innovation (Science), Seed2Sapling Education Foundation, Bengaluru Vijay Pal Singh, Professor, Department of Education in Science and Mathematics, NCERT, New Delhi Reviewers Aditi Murlidhar, Scientific Officer, Homi Bhabha Centre for Science Education, TIFR, Mumbai Ankush Gupta, Associate Professor, Homi Bhabha Centre for Science Education, TIFR, Mumbai Anurag Behar, CEO, Azim Premji Foundation, Member, National Curriculum Framework Oversight Committee xiii 0 Prelims.indd 13 10-07-2024 18:12:45  B. K. Sharma, Former Professor, Department of Education in Science and Mathematics, NCERT, New Delhi Gajanan Londhe, Director, Samvit Research Foundation, Bengaluru K. K. Arora, Former Professor, Zakir Husain Delhi College, University of Delhi, Delhi Manjul Bhargava, Professor, Princeton University & Co-Chairperson, NSTC Manjushree Chaudhuri, Former PGT (Physics), Delhi Public School, R.K. Puram, New Delhi, La Grande Boissière Campus of International School, Geneva Mridula Arora, Principal, Navyug School, Sarojini Nagar, New Delhi Pushpa Tyagi, Former Head of Department (Physics), Sanskriti School, Chanakyapuri, New Delhi and Former PGT (Physics), Kendriya Vidyalaya, Delhi Ravi S. Nanjundiah, Professor, Centre for Atmospheric and Oceanic Sciences (CAOS), Indian Institute of Science, Bengaluru Sanjay P. Sane, Professor, National Centre for Biological Sciences, TIFR, Bengaluru Savita Ladage, Professor, Homi Bhabha Centre for Science Education, TIFR, Mumbai Surendra Ghaskadbi, Former Scientist G, Agharkar Research Institute, Pune Vijay Sarda, Former Associate Professor, Zakir Hussain Dellhi College, University of Delhi, Delhi V. P. Srivastava, Former Professor, Department of Education in Science and Mathematics, NCERT, New Delhi Member-convener, Curricular Area Group (Science) Anjni Koul, Professor, Department of Education in Science and Mathematics, NCERT, New Delhi (Coordinator, Chemistry Sub-group) xiv 0 Prelims.indd 14 10-07-2024 18:12:45  Acknowledgements The National Council of Educational Research and Training (NCERT) acknowledges the guidance and support of the esteemed Chairperson and members of the Curricular Area Group (CAG): Science and other concerned CAGs for their guidelines on cross-cutting themes in developing this textbook. The Council is grateful to the members of the Textbook Development Team, for their contribution in the development of this textbook. The Council also gratefully acknowledges the contribution of the participating members for giving inputs in refining of the textbook—Ankita Dureja, TGT Science, DAV Public School, Gurugram; Anupa Kumbhar, Assistant Professor, Savitribai Phule Pune University, Pune; Ganti S. Murthy, Professor, IIT Indore; Jatinder Mohan Mishra, Professor, DEL, NCERT, New Delhi; Lalmin Kipgen, Assistant Professor, Division of Educational Kits, NCERT, New Delhi; Mayuri Rege, Reader, HBCSE, TIFR, Mumbai; Meenakshi, Assistant Professor, DEL, NCERT; Michel Danino, Visiting Professor, IIT Gandhinagar, Gujarat; Neeraja Dashaputre, Assistant Professor, IISER, Pune; Paresh Joshi, Professor, HBCSE, TIFR, Mumbai; Poonam Bhadoria, Ph.D Scholar, IIT Varanasi; P. V. Raghavendra, Associate Professor, DESM, NCERT, New Delhi; Rahul S. Chatterjee, Assistant Lecturer (Physics), Boys’ Higher Secondary School, Shillong; Rama P. Jayasundar, Head, Department of NMR, AIIMS, New Delhi; Saket Bahuguna, Assistant Professor (Linguistics), Central Institute of Hindi, Delhi Centre, Ministry of Education, Government of India; Santosh Gharpure, Professor, IIT Bombay; Shirish Pathare, Scientific Officer, HBCSE, TIFR, Mumbai; Sudesh Kumar, Associate Professor, DESM, NCERT; Vijay Singh, Former Professor, IIT Kanpur, Former Professor, HBCSE, TIFR, Mumbai, Visiting Professor, Centre for Excellence in Basic Sciences (CEBS), Mumbai; V. P. Arya, Assistant Professor, Regional Institute of Education, NCERT, Ajmer; V. Ramanathan, Assistant Professor, IIT BHU, Varanasi. The Council is thankful to Manoj Nair, Scientific Officer, HBCSE, TIFR, Mumbai for making some of the illustrations for Chapter 7 ‘Temperature and its Measurement.’ The Council is also thankful 0 Prelims.indd 15 10-07-2024 18:12:45  to L. N. Aggarwal, Former Director, Geological Survey of India; R. Shankar, Former Professor, Mangalore University; Ravi Korishettar, Adjunct Professor, National Institute of Advance Studies, Bengaluru; Prabhakar Sangurmath, Former Executive Director, Hutti Gold Mines Company Limited, Bengaluru for providing some photographs of rocks and minerals for Chapter 11 ‘Nature’s Treasures.’ The Council is also thankful to Dorje Angchuk, Engineer-in-charge, Indian Astronomical Observatory (IIA), Hanle, Ladakh for providing the photographs and to Pritesh Ranadive, Scientific Officer, HBCSE, TIFR, Mumbai for providing some illustrations from Stellarium (a free open-source planetarium) for Chapter 12 ‘Beyond Earth.’ Acknowledgements are due to Sridhar Srivastava, Joint Director, NCERT; Amrendra P. Behera, Joint Director, CIET, NCERT; Ranjana Arora, Professor and Head, DCS&D, NCERT; Sunita Farkya, Professor and Head, DESM, NCERT, New Delhi for providing academic, administrative and technical support. The Council is thankful to Fanindra Sharma, Consultant, Programme Office, NSTC, NCERT, New Delhi; M Pramod Kumar, Senior Consultant, Programme Office, Assistant Professor, Amrita Darshanam Centre, Amrita Vishwa Vidyapeetham, Coimbatore; Suparna Diwakar, Educator and Development Sector Professional and Chief Consultant, Programme Office, NSTC, NCERT, New Delhi. The Council acknowledges the efforts of Annu Dahiya, Archana, Neha Dhingra, Manish Joshi, Tanya Kaur, Senior Research Associates, Nitika Rani, Course Administrator, and Neha Yadav, Junior Project Fellow, DESM, NCERT, New Delhi; and the support provided by the APC office and administrative staff of DESM. Acknowledgements are due to Ankeeta Bezboruah, Freelance Editor and Mathew John, Former Editor, NCERT, New Delhi, for their valuable assistance in editing the manuscript of this textbook. The Council acknowledges the contribution of Pawan Kumar Barriar, In-charge, DTP Cell, Publication Division, NCERT; Vipan Kumar Sharma, Manoj Kumar, Shiv Shankar Dubey, and Rajshree Saini, DTP Operators (Contractual), Publication Division, NCERT for giving this document a final shape. 0 Prelims.indd 16 10-07-2024 18:12:45  Contents Foreword iii About the Book v Chapter 1 The Wonderful World of Science 1 Chapter 2 Diversity in the Living World 9 Chapter 3 Mindful Eating: A Path to a Healthy Body 35 Chapter 4 Exploring Magnets 61 Chapter 5 Measurement of Length and Motion 79 Chapter 6 Materials Around Us 101 Chapter 7 Temperature and its Measurement 123 Chapter 8 A Journey through States of Water 143 Chapter 9 Methods of Separation in Everyday Life 163 Chapter 10 Living Creatures: Exploring their Characteristics 183 Chapter 11 Nature’s Treasures 207 Chapter 12 Beyond Earth 231 0 Prelims.indd 17 10-07-2024 18:12:45 0 Prelims.indd 18 10-07-2024 18:12:45  Chapter 1 The Wonderful World of Science As human beings, we have always been curious about our surroundings. We start exploring our surroundings and asking questions right from our childhood. Did you enjoy discovering and exploring the world around you in the Preparatory Stage of school? As you enter the Middle Stage, we will continue this fascinating journey, trying to explore and understand the beautiful world we live in. And for that, we have a new subject, Science. Welcome to the ? wonderful world of Science! Science is a way of thinking, observing and What is doing things to understand the world we live in Science? and to uncover the secrets of the universe. Think of it as a big adventure—we ask questions, explore the world and try to understand how things work. For this, the most important thing is to have ‘Curiosity’, which is where the title of this book comes from. Whether it is studying tiny grains of sand or massive mountains, a leaf of grass or a vast forest, there is always something new and exciting to discover. Have you ever looked up at the night sky and wondered why the stars shine? Or watched a flower bloom and wondered how it knows when to open? These are just a few of the many mysteries that science helps us unravel. The most wonderful thing about science is that it is everywhere. From the depths of the ocean to the A mountainous region Chapter 1.indd 1 09-07-2024 10:19:44  A Desert A Coast vastness of outer space, from what is cooking in the kitchen to what is happening on the playground, some of the most groundbreaking discoveries have often come from unexpected places. An underwater view of an Ocean A Galaxy Curiosity | Textbook of Science | Grade 6 Science is like a giant and unending jigsaw puzzle. Every new discovery we make adds another piece to that puzzle. And you know the best thing about this puzzle? There is no limit to what we can discover, since every new piece of knowledge leads to more questions and more things to find out. Sometimes, we find that a piece of this puzzle has been put in the wrong place and needs to be moved. New discoveries often change our understanding of the world. As you go through this book, you will encounter interesting ideas, do some thought-provoking experiments, and see how some of what we will find out is useful in our 2 Chapter 1.indd 2 08-07-2024 05:23:26 PM  daily lives. And guess what happens as we ? discover more and more? We start realising What will we that these ideas are all connected. explore with We will start off by looking at our the help of this home, planet Earth. It is the only planet book? we know that supports life, and it has an environment that we must protect. There is an amazing variety of life on Earth—plants and animals that have managed to survive and thrive in different regions on this planet. You might have seen a seed grow into a plant, a caterpillar transform into a beautiful butterfly and many more such observations. How do these plants and animals grow? Of course, to grow, we need food to eat, and especially in a large and diverse country like India, food is so fascinating. Across the country, we have different cuisines with their many tasty dishes. What are they made of? How do we find out? The Wonderful World of Science 3 Chapter 1.indd 3 08-07-2024 05:23:39 PM  Along with food, we need water to survive. Water is such a delightful substance. Have you ever run and jumped in a puddle when it rained? Do you ever wonder why and how it rains? Have you noticed that water freezes and becomes ice when we cool it and boils and becomes steam when we heat it? Do you enjoy drinking cool water in the summer or showering with warm water in the winter? How do we understand hot and cold? Whether it is water, or our own body when we have fever, finding out how hot something is can be important! Then again, there are so many different things around us—the paper we write on, the metal key, the plastic ruler and the rubber eraser in our box, the magnet that keeps the box closed, the clothes we wear, the cup we drink milk in and so many other things. What are they made of? Are they made of different materials? How do we separate different materials from one another? Curiosity | Textbook of Science | Grade 6 4 Chapter 1.indd 4 08-07-2024 05:23:48 PM  We will have an almost unending list of questions about everything on Earth as we further explore this book. But why limit our questions to the Earth alone? We can ask questions on things beyond—the Sun, the Moon, and the millions of stars that shine in the sky! Whether you are learning about the ? structure of a leaf, discovering how things How can we try move, or separating the skin of a peanut seed, to find answers we hope each chapter of this book will ignite to our questions your spirit of inquiry. And hopefully you will on our own? have lots of questions in your mind! Even though you may not realise it, you have already been finding answers to many of your questions. Suppose your pen stops writing. What would you do? You would ask yourself the question, “Why did my pen stop writing?”. You might guess that the ink finished. You would then test this guess by opening the pen and checking the ink refill. If it is empty, you would know that your guess was correct. But suppose you find that the ink was not finished. Now what would you do? You would make another guess—perhaps the ink might have dried up. To test if this guess is correct or not, you will try something else. This is exactly how Science works! The way you tried to find out why your pen stopped writing is an example of the scientific method. Activity 1: Let us think and write The Wonderful World of Science ‹‹ Write about a similar problem that you tried to solve. ‹‹ What steps did you take? Science is not just about memorising facts and figures or doing experiments. It is about following a step-by-step process that helps us find answers to our questions. So what are the steps that we can follow? 5 Chapter 1.indd 5 08-07-2024 05:23:50 PM  First, we observe something that we find interesting or we do not understand. This makes us wonder and perhaps think of a question about it. Then, we guess a possible answer to that question. We test this guess through experiments or more observations. We then try to analyse the results to see if it actually answered our question. Scientists are people who follow the scientific method to solve problems or to discover new things. But anyone who follows the scientific method is working like a scientist. Someone cooking food may be wondering why the dal has spilled out of the cooker—was there too much water? Think of a bicycle repair person trying to find out why a tyre is flat—from where did the air leak out? Or an electrician trying to find why a light bulb is not working—is there some Curiosity | Textbook of Science | Grade 6 problem with the bulb or the switch? When we try to ask questions and find out answers, in a way, we are all scientists! Activity 2: Let us think and write ‹‹ Describe a daily life situation where you feel someone was following a scientific method. Do you now realise that there are several daily life situations where we knowingly or unknowingly apply the scientific 6 Chapter 1.indd 6 08-07-2024 05:23:53 PM  method? Though we all apply the scientific method to some extent, learning science will develop our capabilities for finding solutions to bigger problems and solving more mysteries of the universe. And to be able to learn science well, the first and foremost thing is to be curious and observe your surroundings keenly. And when we are curious, we start posing questions, asking how and why? Just remember, the world is full of things we do not know, things that are waiting to be explored. Activity 3: Let us think and write ‹‹ If you have to ask “Why?” about something, what would you ask about? ‹‹ Try to write down how you would attempt to find an answer to your question. Science is rarely done alone. Scientists across the world work together, often in large teams. So, if you cannot find an answer yourself, ask your friends to help you out! It is always more fun to discover things together. The Wonderful World of Science Of course, remember that you will not find answers to all your questions within Grade 6. Do not worry, you are embarking upon a journey of science for the next five years or even beyond! 7 Chapter 1.indd 7 08-07-2024 05:23:55 PM  ? Much like children enjoying After all, to be the rain, science is all about joyful a wise person, exploration. Enjoy your scientific you must be a journey, keep exploring and never “whys” person! stop wondering about the amazing mysteries of the universe and asking questions. Are you ready to embark upon the exciting journey of Science? Let us get started!! Curiosity | Textbook of Science | Grade 6 8 Chapter 1.indd 8 08-07-2024 05:23:57 PM  Chapter 2 Diversity in the Living World छायामन्यस्य कुर्वन्ति तिष्ठन्ति स्वयमातपे । फलान्यपि परार्थाय वक ृ ्षाः सत्पुरुषा इव ॥ (सभ ु ाषित) Trees stand in the Sun and give shade to others. Their fruits are also for others. Likewise, good people bear all hardships and bring welfare to others. They give to others whatever they have earned. (Wise saying) It is a pleasant morning after yesterday’s refreshing rain. Dr Raghu and Maniram chacha (uncle) have been invited to the school by the science teacher, Madam Sulekha, to Chapter 2.indd 9 10-07-2024 18:14:30  facilitate an exciting nature walk. Dr Raghu is a scientist at the nearby Research Laboratory and Maniram chacha is an elderly person from a nearby community. Maniram chacha is an expert in mimicking bird calls. He is also brilliant at identifying a variety of plants and animals. To prepare them for the nature walk, Dr Raghu informs the students that the objective of this walk is to experience the beauty and variety of plants and animals in the nature. The students are excited to join them. They are curious to interact and learn from them. The teacher advises the students to carry a notebook, a pen and a water bottle. As they walk, they begin exploring the plants and animals around them. Dr Raghu advises the students to notice the variety of smells in the park and emphasises respecting all living creatures and observing them without disturbing. Maniram chacha tells the students to not only observe different plants and animals but also to carefully listen to different sounds. The students come across a variety of plants, including grasses, bushes, and large trees. They also observe a variety Wow! It is of birds sitting on the branches of trees, butterflies moving amazing how each bird has from flower to flower and monkeys jumping from one tree its own unique to another. They record their observations in their notebooks chirp. and discuss them with Dr Raghu and Maniram chacha. The students can hear the chirping of birds. Dr Raghu informs them that each bird has a unique chirp. This is an example of diversity in nature. Dr Raghu requests Maniram chacha to mimic calls of some birds. Maniram chacha mimics different bird calls. The students enthusiastically start copying him. Have you ever observed different plants and animals Curiosity | Textbook of Science | Grade 6 around you? Share and discuss your observations with your friends and teacher. 2.1 Diversity in Plants and Animals Around Us Activity 2.1: Let us explore and record ‹‹ Plan for a nature walk with your teacher to a park or a nearby forest. ‹‹ While on the nature walk, observe different plants, insects, birds, and other animals. Also, note the weather 10 conditions, whether it is hot, cold, windy and so on. Chapter 2.indd 10 10-07-2024 18:14:45  ‹‹ You can collect different types of fallen leaves or flowers and create a scrapbook. ‹‹ Take care of the plants and animals in nature. Ensure that you do not disturb the plants and animals in the park. Do not pluck leaves and flowers. ‹‹ Record your observations in Table 2.1 about the features of stems, leaves, flowers and anything interesting in various plants. Some examples have been given for you in Fig. 2.1 and Table 2.1. (a) Grass (b) Tulsi (Holy Basil) (c) Hibiscus (Gudhal) Fig. 2.1: Examples of different features of some plants Table 2.1: Observations of different plants around us Local Leaves (shape/ Any other S. no. name of Stem arrangement of Flowers observations plant leaves) and features A single leaf grows Common Soft and alternatively from 1. Green leaves grass thin different points on the stem Arrangement of Hard a pair of leaves Pinkish 2. Tulsi and thin in the opposite purple Diversity in the Living World directions 3. Hibiscus Hard Hard Leaves with 4. Neem and smooth thick surfaces 5. Any other 11 Chapter 2.indd 11 10-07-2024 18:15:04  What similarities and differences did you find among the plants that you observed? You must have observed that plants have a variety of features such as— ‹‹ tall/short, hard/soft stem ‹‹ different shapes of leaves and their arrangement on the stem or branches ‹‹ flowers varying in colour, shape, and scent Now, create a list of animals you observed during this walk or from your previous experiences. Record the places where they live, the food they eat and the ways they move around in Table 2.2. Some examples have been provided for you. Table 2.2: Observations of different animals around us Name of Place where Food they The way Any other the animal they live eat they move observations (local name) around and features Carrying a Crow Tree Insects Fly and walk twig in its beak Nest in soil Leaves, seeds Ant Have six legs and burrow and insects Grasses, Cow leaves Any other Curiosity | Textbook of Science | Grade 6 What are the similarities and differences among the animals that you have observed and recorded in Table 2.2? You would have observed that some animals live on land while some others live on trees. Birds live on trees. Fish live in water and some animals like frogs live on land as well as in water. Animals also have a variety of foods they consume and movements they exhibit. Sketch the plants and animals observed by you in your notebook or prepare a scrapbook with leaves, flowers from different plants and feathers from animals. Write all the 12 details you have gathered about them. Chapter 2.indd 12 10-07-2024 18:15:04  While travelling to and from school, observe your surroundings and look out for a variety of plants and animals. Add the name of any plant or animal that you have not listed before in Tables 2.1 and 2.2. Activity 2.2: Let us appreciate ‹‹ Close your eyes for 30 seconds and think of one plant and one animal that you have closely observed and have appreciated very much. ‹‹ Now each one of you can draw the plant and animal that you thought of on the blackboard. ‹‹ What are your observations about the various plants and animals that have been drawn? Diversity in the Living World ‹‹ How many different plants and animals did the entire class draw on the blackboard? ‹‹ Do you think that there may be many more varieties of plants and animals other than those drawn on the board? The variety of plants and animals found in a particular region contributes to the biodiversity of that region. 13 Chapter 2.indd 13 10-07-2024 18:15:06  Each member in the biodiversity of a region has a different role to play. For example, trees provide food and shelter to some birds and other animals, animals help in spreading seeds after eating fruits, and so on. Can you think of more such examples? This shows that plants and animals are dependent on each other. 2.2 How to Group Plants and Animals? How would you arrange your books and notebooks in groups? Would arranging them in groups help you better organise your school bag? Now, let us look at the world around us. We are surrounded by a variety of plants and animals with different features about which you have learnt in section 2.1. We can group them based on similarities and differences among them. Activity 2.3: Let us group ‹‹ Collect pictures of various other plants and animals. Cut their pictures from old magazines, newspapers, charts and other sources. Paste each of these pictures on a different card. ‹‹ Divide your class in groups of 5–6 students each. ‹‹ Pool the cards prepared by the students in your group. ‹‹ Observe various features of plants and animals shown on the cards. ‹‹ Recall the features of plants and animals that you have listed in Tables 2.1 and 2.2. Group them on the basis of common features. Curiosity | Textbook of Science | Grade 6 ‹‹ ‹‹ Share and discuss the basis of grouping you have made with other groups in your class. You will be surprised to see that the basis used by different groups may vary. What do you think are the reasons behind it? Different students might have chosen different common features for the grouping. For example, some students may have chosen the height of plants as the basis for grouping while others might have chosen presence or absence of flowers as the basis for grouping of plants (See Fig. 2.2). 14 Chapter 2.indd 14 10-07-2024 18:15:06  Presence/ Hard/soft Eating Place they absence of stem habits live flowers Fig. 2.2: Some possible criteria of groupings of plants and animals You may have grouped animals based on varied features, such as what they eat, where they live, what colour they are and how they move. What is the importance of grouping? Grouping makes it easier to understand and study plants and animals on the basis of their similarities and differences. You will learn more about the importance of grouping in our daily lives in the chapter, ‘Materials Around Us’. 2.2.1 How to group plants? You must have noticed that plants show variation in the features related to stems, leaves, flowers, and more. The stems of different plants vary in thickness, height, and hardness, while the leaves vary in shape, colour, size and arrangement. You might have tried grouping the plants in Activity 2.3 using one of these features. You might have also learnt in earlier classes that plants can be grouped into herbs, shrubs, and trees based on their height and types of stem. Let us study the features of plants in more detail and group them on that basis. Activity 2.4: Let us group ‹‹ Let us go on a nature walk again for some more interesting observations. ‹‹ Look closely at the heights of different plants. Are these plants shorter than you, as tall as you, or taller than you? Diversity in the Living World ‹‹ Is the stem brown or green? Touch and feel their stems and try to bend them gently. Can you bend the stem easily, or is it stiff? Take care that stems do not break. ‹‹ Also, observe from where the branches of the plants arise—whether they arise close to the ground or higher up on the stem. Fill in your observations in Table 2.3. A few examples are already given. 15 Chapter 2.indd 15 10-07-2024 18:15:06  Table 2.3: Grouping of plants based on height and nature of stem S. Name of Height Nature of stem Appearance of Name no. the plant branches of plant group Short/ Green/ Tender/ Thick/ Close Higher Medium/ Brown Hard Thin to the up on Tall ground the stem 1. Mango Tall Brown Hard Thick Yes Tree 2. Rose Medium Brown Hard Thin Yes Shrub 3. Tomato Short Green Tender Thin Yes Herb What differences do you observe among herbs, shrubs, and trees? How can you group plants as herbs, shrubs, and trees based on the data entered in Table 2.3? Some plants grow really tall and have hard, thick, brown, and woody stems. Their branches typically start higher up Curiosity | Textbook of Science | Grade 6 on the stem and away from the ground. (a) Tree These plants are called trees. For example, a mango tree (Fig. 2.3a). 16 (b) Shrub (c) Herb Fig. 2.3: Types of plants Chapter 2.indd 16 10-07-2024 18:15:35  Some plants are not as tall as trees. These plants often have many brown woody stems that start branching very close to the ground. These stems are hard but not as thick as the stem of a tree. These plants are called shrubs. For example, a rose plant is a shrub (Fig. 2.3b). Some plants are typically small with soft and green stems. These are known as herbs. For example, a tomato plant is a herb (Fig. 2.3c). Some plants with weak stems need support to climb and grow, and are called climbers. Some plants creep along the ground and are called creepers. What can be other features on the basis of which you can group plants? Let us perform another activity. Activity 2.5: Let us compare ‹‹ Look at the leaves of different plants collected by you, during the nature walk. ‹‹ Do you notice the variation in the shape and structure of these leaves? You may observe thin lines on the leaves of the plants (Fig. 2.4a). These are veins. The pattern of veins on the leaf is called venation. What differences do you see in the veins of leaves shown in Fig. 2.4a and Fig. 2.4b? (a) Hibiscus leaf with (b) Banana leaf with (c) Grass leaf with reticulate venation parallel venation parallel venation Diversity in the Living World Fig. 2.4: Leaves showing different types of venation In some leaves, you can observe a net-like pattern of veins on both sides of a thick middle vein. This pattern is called reticulate venation. For example, leaves of hibiscus exhibit reticulate venation (Fig. 2.4a). In some leaves, you may observe that the veins run parallel. This pattern is called parallel venation. For example, the leaves of banana plants and grasses exhibit parallel venation (Fig. 2.4b and Fig. 2.4c). 17 Chapter 2.indd 17 10-07-2024 18:15:36  Do you think that plants can be grouped on the basis of venation present in their leaves? Now, let us try to explore roots of the plants. Do all plants have roots? Are these roots similar? Activity 2.6: Let us find out ‹‹ Visit an open area where wild herbs and grasses are growing. You may use small herbs for this exercise. ‹‹ Using a khurpi (trowel), carefully dig out a few different herbs without damaging the roots. To do this, you may wet the soil and loosen it. ‹‹ Wash the roots with water and observe them. ‹‹ After you are done observing, make sure to replant the herbs so that they may continue to thrive and grow. What are the similarities and differences in the roots of the plants collected by you? What differences do you see in the roots of plants shown in Fig. 2.5a and Fig. 2.5b? Curiosity | Textbook of Science | Grade 6 (a) Taproot system in (b) Fibrous root system a mustard plant in common grass Fig. 2.5: Types of roots Observe carefully the roots of a mustard plant in Fig. 2.5a. The roots of this plant consist of one main root and small side roots arising from it. The main root is called taproot. Another example of a plant having taproots is hibiscus observed by you in Activity 2.1. The plant in Fig. 2.5b is a common grass plant. The roots of this plant appear as a bunch of similar-sized thin roots arising from the base of the stem. Such roots are called fibrous roots (Fig. 2.5b). 18 Does your collection include any other grasses? What kind of roots do they have? Chapter 2.indd 18 10-07-2024 18:16:03  Is there any relation between the type of leaf venation and the type of root of the same plant? How do we find this out? Activity 2.7: Let us relate and analyse ‹‹ Collect saplings of five common plants from your school nursery or any other nurseries to plant in your school garden. Examples of such plants can include lemongrass, marigold, sadabahar (periwinkle), and others. ‹‹ Before planting them, observe their roots and the venation in their leaves. ‹‹ Record your observations in Table 2.4. Table 2.4: Types of leaf venation and roots S. no. Name of the Type of leaf Type of root plant venation (fibrous/tap) (reticulate/ parallel) 1. Lemongrass Parallel Fibrous 2. 3. 4. 5. Do you observe any relation between the leaf venation and types of root in these plants? A sadabahar plant has a taproot and its leaves have reticulate venation. Do Diversity in the Living World other plants with reticulate venation have taproots too? Lemongrass, on the other hand, has fibrous roots and its leaves have parallel venation. Do other plants with parallel venation have fibrous roots too? Generally, plants with reticulate venation have taproots while those with parallel venation have fibrous roots. Chickpea (chana) is another example of a plant with taproots and reticulate venation in leaves. Wheat is an example of a plant with fibrous roots and parallel venation 19 in its leaves. Chapter 2.indd 19 10-07-2024 18:16:03  Is there any relation among the seed of a plant, types of root and leaf venation? Are all seeds similar? Activity 2.8: Let us compare ‹‹ Soak some chickpea and maize seeds in water for two or three days. ‹‹ Remove the seed coat of a chickpea. Now, observe the structure of the chickpea and maize seeds. Are they similar or different? Cotyledons (a) Dicot seed (chickpea) (b) Monocot seed (maize) Fig. 2.6: Dicot and monocot seeds You would notice that chickpea seeds are split into two parts (Fig. 2.6a). Each part is called a cotyledon. Plants that have seeds with two cotyledons are called dicotyledons (dicots). Maize has a single thin cotyledon (Fig. 2.6b). Plants with such seeds are called monocotyledons (monocots). What relation do you observe among leaf venation, root types and the number of cotyledons in seeds of a plant? Dicot plants have reticulate venation and a taproot system while monocot plants have parallel venation and a fibrous root system. Curiosity | Textbook of Science | Grade 6 You have learnt about some features used for grouping plants. Now, let us explore the grouping of animals in more detail. 2.2.2 How to group animals? Just like plants, animals too are significantly different from one another. How can we group such a wide variety of animals? What features can you think of to group them? In Activity 2.3, you have already set some bases for grouping