Measurement - Accuracy and Precision (Science)

Measurements Accuracy and Precision Measurements In science classes you will make many different kinds of measurements using many different kinds of tools and equipment. Measuring skillfully is critical to scientists and engineers, and measuring is something everyone does every day....

Measurements Accuracy and Precision Measurements In science classes you will make many different kinds of measurements using many different kinds of tools and equipment. Measuring skillfully is critical to scientists and engineers, and measuring is something everyone does every day. The word “measure” comes from the greek “metron” which What is measurement, and why is it important? means “to moderate” or “to compare with a standard”. Other words that come from that same root include: Meter Metronome Symmetry  Describe the following images Quantitative and Qualitative using quantitative and qualitative measurements: Making measurements uses tools to determine properties or traits. This observed data can be classified as quantitative or qualitative: Quantitative data: is based on numbers or measurements using tools. Qualitative data: is based on interpretation or description.  Quantitative and Qualitative practice Determine if the following are Which type of quantitative or qualitative measurement do measurements: you think is better for science class, Mr. John is 177.8 cm tall quantitative or Timothée Chalamet has black hair qualitative? Ms. Anderson is very funny! Oregon is 8824.03 km from Jeju Why?  Time Measuring Tools Good measurements require the proper tools AND the skill Lengths and angles to use them! What tools are used in measurement? What are those tools used to measure? Volumes What is a unit of measurement? Masses and weights  Wait, does this word “metric” sound familiar? “Metric” refers to the “meter” - an early Metric System standard measurement! The metric system includes the Distance Meters (m), standard units of measurement that Centimeters (cm), you will use in science classes Millimeters (mm), Kilometers (km) Most of the world uses metric units, but Volume some people are not familiar with Liters (L) them! Mass Milliliters (mL) Grams (g), The metric system consists of units for Milligrams (mg), measuring many variables including: Kilograms (kg) Do you notice any patterns? Metric System Conversion The metric system is consistent and easy to use, even when comparing different types of units or measurements. This is because the metric system uses the same scale Meters Grams for all measurements! So Liters Convenient! etc. Different instruments may also use different scales! These arrows all indicate 25cm on tools that each use a different scale How to make a measurement Making a measurement as accurately and precisely as possible is important. Your measurements will always depend on the precision of your tools! When using a tool to measure, it is proper to first measure and then estimate one decimal place past what you can clearly see! How to make a measurement - practice Let’s practice measuring the lines using the ruler here (not to scale) 4.42 cm 3.20 cm  How to measure liquids Measuring liquids can be tricky because they will often stick to the sides of a measuring device and will not show a straight line. The curve at the top of a column of water is called the “meniscus”; which Assuming this cylinder is measuring comes from the Greek “meniskos” milliliters, how much water is in the (meaning “crescent”). tube above? This is also where “moon” comes from! Always measure from the BOTTOM of the meniscus! 21.69 mL Measurement and Error Let’s measure some water! 1. Carefully measure 100 mL of water into a beaker. 2. Pour your measured water into the graduated cylinder 3. What do you notice?! Because measurements are based on Turn & Talk: imperfect tools and imperfect observers, all measurements have error! Explain what this statement means to a person sitting next to you. Graduated Cylinder Get their name from the scale (or ‘graduations”) on the side of the cylinder As a measurement tool, graduated cylinders have a higher precision than beakers! Explain the above statement with someone at a different table than you. Measurement - Accuracy and Precision When making measurements it is important to understand what can affect the validity and credibility of our data. Accuracy: is a measurement of how close our data matches the correct (or accepted) value Precision: is a measurement of how consistent (or close to each other) our data are Why does our experimental data need to have both in order to be valid and credible? Accuracy and Precision Example Measurement - Accuracy and Precision Remember! Measurements will ALWAYS be limited by: 1. The accuracy of the measurer (these are often the same person) 2. The accuracy of the observer 3. The precision of the measurement device or tool Practice making accurate measurements to the highest possible precision by completing the measurements worksheet When you are finished, attach the worksheet in your science notebook