Using evidence to answer questions

Think about your favorite games. A soccer ball moves when you kick it. It slows down when it rolls on the grass. Scientists ask questions about these changes, just like you can.

In this unit, kids pass a soccer ball back and forth. They stand close together, then far apart. They watch what happens to the ball each time. They look for things that are the same and things that are different.

Then comes the science part. When two things bump into each other, something called energy moves from one to the other. How do we know? We look for evidence. Evidence is what we can see and measure. Did the second object start to move? Did its shape change? Those changes are our clues.

Scientists use clues like these to answer questions. If you say energy moved, you must point to the change you saw.

Have you ever had a clock stop working? What made it stop? That is a science question, and you can answer it with evidence.

In this unit, kids look at two kinds of clocks. One clock you wind up. The other clock plugs into the wall. Kids watch both clocks and write down what they see. They find things that are the same. Both clocks keep time. Both need energy to work. They also find things that are different. One uses a spring, and one uses electricity.

Then kids go on tours of their school, open up old devices, and build simple circuits. Each time, they gather clues about what makes things turn on and stay on.

When you compare two things and list what is the same and what is different, you are doing science. Those lists are evidence you can use to answer questions like, why did the clock stop?

Scientists collect information to answer their questions. There are two kinds of information.

The first kind is called quantitative. That is a big word that means you can count it or measure it. How many birds came to the feeder? How tall did the plant grow? Numbers are quantitative information.

The second kind is called qualitative. That means you describe it with words instead of numbers. What color was the bird? Did the plant look healthy or droopy? Descriptions are qualitative information.

Both kinds help scientists. A scientist might count ten red birds and two blue birds at a feeder. Then she can answer the question, which birds visit most? Her counts are her evidence.

Scientists also follow steps called the scientific method. They ask a question, make a guess, gather information, and use that information as evidence to find the answer. You can do the same thing when you are curious about the world.