1. Section 1 Tools and Models in Science Chapter 2 Tools in Science A tool is anything that helps you do a task. Scientists use many different tools to help them make observations, take measurements, and analyze data.

2. Section 1 Tools and Models in Science Chapter 2 Making Measurements The International System of Units (SI) is the standard system of measurement. All SI units are expressed in multiples of 10. Prefixes are used to express SI units that are larger or smaller than basic units. For example, kilo- means 1,000 times, and milli- indicates 1/1,000 times.

3. Section 1 Tools and Models in Science Chapter 2 Making Measurements, continued Length, mass, volume, density, and temperature are common measurements. The meter is the basic SI unit of length. The kilogram (kg) is the basic SI unit for mass. Mass is the measure of the amount of matter in an object.

4. Section 1 Tools and Models in Science Chapter 2 Making Measurements, continued Liquid volume is expressed in liters (L). Volume is a measure of the size of an object in three-dimensional space. The volume of solid objects is usually expressed in cubic meters (m3).

5. Section 1 Tools and Models in Science Chapter 2 Making Measurements, continued Density is the ratio of the mass of a substance to the volume of the substance. The temperature of a substance is a measurement of how hot the substance is. The kelvin (K) is the SI unit for temperature.

6. Data in Science Chapter 2

7. Section 1 Tools and Models in Science Chapter 2 Models in Science A model is a representation of an object or system. A model uses something familiar to help you understand something that is not familiar. Physical, conceptual, and mathematical models are commonly used in science. Models have limitations because they are never exactly like the real thing.

8. Section 1 Tools and Models in Science Chapter 2 Using Models for Scientific Progress In science, a theory is a system of ideas that explains many related observations and is supported by a large body of evidence acquired through scientific investigation. In science, a law is a descriptive statement or equation that reliably predicts events under certain conditions.