Rocket and Raven carry a flat basketball to the driveway. It thumps and does not bounce.
"It just needs more air," Rocket says, and he grabs the hand pump.
With every push, the ball grows firmer. Raven presses her thumb into it. "What do you notice?" she asks.
"It is harder now," Rocket says. "But we put in something invisible."
Nova circles the ball. "I found a pattern," she says. "More air particles squeezed inside means a firmer ball."
You cannot see particles, but you use them every day. Here are three examples scientists use as evidence that matter is made of particles.
| What happens | What the particles are doing |
|---|---|
| Pumping air into a basketball makes it firm. | More gas particles are pushed into the same space. |
| Sugar seems to vanish in water. | Sugar particles spread out through the water. |
| Salt water dries up and leaves crystals. | Water particles leave as a gas; salt particles stay. |
One idea explains the basketball, the sugar and the salt water.
All matter is made of particles too small to see.
When you can explain many events with one idea, that idea is very useful in science.
| Statement | True or false? |
|---|---|
| Pumping air into a ball pushes more gas particles into the same space. | ? |
| A flat ball has no air particles inside. | ? |
| Sugar particles spread through water when it dissolves. | ? |
| Salt water drying up leaves salt behind. | ? |
You explained real events with invisible particles. That is how scientists think. Tomorrow is Launch Lab with your family.