Measurement & Scientific Tools Lesson 2

Measurement and Scientific Tools What is the difference between accuracy and precision? Why should you use significant digits? What are some tools used by scientists?

Measurement and Scientific Tools Vocabulary description explanation International System of Units (SI) accuracy precision significant digits

Measurement and Scientific Tools Description & Explanation A description is a spoken or written summary of observations. An explanation is an interpretation of observations. When you explain something, you try to interpret your observations, which can lead to a hypothesis.

Measurement and Scientific Tools The International System of Units The International System of Units (SI) is an internationally accepted system for measurement. All SI units are derived from seven base units.

The International System of Units (cont.) A prefix can be added to a base unit’s name to indicate either a fraction or a multiple of that base unit. Prefixes are based on powers of ten, such as 0.01 and 100.

Measurement and Scientific Tools Accuracy & Precision Accuracy is a description of how close a measurement is to an accepted or true value. Precision is a description of how similar or close measurements are to each other.

Measurement and Scientific Tools Accuracy & Precision The data taken by student A are more accurate because each value is close to the accepted value. The data taken by student C are more precise because the data are similar.

Measurement and Scientific Tools The International System of Units (cont.) How do accuracy and precision differ?

Measurement and Scientific Tools Measurement and Accuracy All measurements have some uncertainty. The tools used to make measurements limit the accuracy of the measurements.

Measurement and Scientific Tools Significant Digits Significant digits are the number of digits in a measurement that are known with a certain degree of reliability. The significant digits in a measurement include all digits you know for certain plus one estimated digit.

Measurement and Scientific Tools Significant Digits

Measurement and Scientific Tools Significant Digits (cont.) Using significant digits lets others know how certain your measurements are.

Measurement and Scientific Tools Significant Digits (cont.) Why should you use significant digits?

Measurement and Scientific Tools Science journals are for recording descriptions, explanations, plans, and steps used in scientific inquiry (The Scientific Method).

Measurement and Scientific Tools Scientific Tools (cont.) A triple-beam balance or a digital balance is used by scientists to measure mass.

Measurement and Scientific Tools Scientific Tools (cont.) A thermometer measures the temperatures of substances.

Measurement and Scientific Tools Scientific Tools (cont.) Flasks, beakers, petri dishes, test tubes, and specimen jars are used as containers.

Measurement and Scientific Tools Scientific Tools (cont.) Graduated cylinders are used to measure the volume of a liquid. The unit of measure for liquid volume is the liter (L) or milliliter (mL).

Measurement and Scientific Tools Scientific Tools (cont.) Microscopes, such as dissecting microscopes and compound light microscopes, enable you to observe small objects that you cannot observe with just your eyes.

Measurement and Scientific Tools Scientific Tools (cont.) Scientists use computers to compile, retrieve, and analyze data for reports.

Measurement and Scientific Tools Tools Used by Life Scientists A magnifying lens is a hand-held lens that magnifies, or enlarges, an image of an object. To observe items using a compound light microscope, you must place it on a thin, rectangular piece of glass called a slide.

Measurement and Scientific Tools Tools Used by Life Scientists (cont.) Scientists use dissecting tools, such as scalpels and scissors, to examine tissues, organs, or prepared organisms. A pipette is a small glass or plastic tube used to draw up and transfer liquids.

Measurement and Scientific Tools Tools Used by Life Scientists (cont.) What are some tools used by life scientists?