CHAPTER 1: THE METRIC SYSTEM

Chapter 1, Lesson 1

LESSON 1: WHAT IS PHYSICAL SCIENCE? Physical science is the study of

things around you. It deals with matter and energy.

THE STUDY OF MATTER AND ENERGY

What do we have in common with all the objects around us? (ex: desk, floor, air) We are all made up of matter. Matter is anything that takes up space. All matter has mass. Mass is the amount of material that an object has. Energy is different from matter. You cannot hold energy or measure it with a ruler. Energy is needed to make things move. Ex: you need it to move, cars need it to run.

TWO AREAS OF PHYSICAL SCIENCE

Physical scientists study many different things. Physical science can be divided into two areas: chemistry and physics.

Chemistry is the study of matter and how it changes. Ex: How does a cake rise or how does acid rain form? Chemistry is also the study of how matter can be made into new materials. Ex: new medicines, food, clothing, fragrances, soaps, artificial skin and artificial bones.

Physics is another area of physical science. Physics is the study of energy and how it acts with matter. Ex: It explains how helium balloons rise or how lasers work. Scientists studying physics have developed TV, cell phones, stereo systems, computers, space satellites, microwave ovens, and jet airplanes.

THE TOOLS OF PHYSICAL SCIENTISTS

All scientists need many different skills. They also need to be curious about things. They want to know why sugar dissolves in water but sand does not. They like to figure out how and why things are the way they are. They answer their questions by doing experiments. In order to answer their questions, they need scientific tools. They also need to know how to make measurements. Measurements are important in gathering information.

LESSON 2: WHY DO SCIENTISTS MEASURE?

Look at the picture of the lines above. Which one is the longest? Use a ruler to measure each one.

Are you surprised at the results?

Measurements are important because we cannot always trust our eyes to make accurate observations.

Measurements help us gather exact information and obtaining exact measurements are important to scientists

UNITS OF MEASUREMENT

What unit of measurement did you use to measure the lines? You probably used a ruler marked in inches. Inches are a known amount of measurement for you. This known amount is called a unit. Other units you are familiar with are yard, mile, minute and day.

Thousands of years ago, people used body parts to measure. For example: Egyptians used the cubit to measure length. A cubit was the distance from the elbow to the tip of the middle finger. Romans used an uncia to measure length. An uncia was the width of their thumb.

If we compare the width of each person’s thumb in this classroom, would they all be the same? Using units of measurement based on body parts does not work well. In order for a unit of measurement to be useful, it has to be the same for everyone. In order to share information with others, the measurement must mean the same for both of them.

SYSTEMS OF MEASUREMENT

We measure in units based on the English system. You should be familiar with the English system units: inch, foot, yard and mile. We also use the English system to measure time, weight and other amounts.

Scientists and most other people throughout the world use a different system of measurement. They use the metric system. Metric units are the most common units of measurement in the world. The metric system is simpler to use and easier to remember.