Weather Machine

Little levels (ages 4 to 6)

1. Make a cloud Turn up the heat and the water and watch vapor rise into a cloud.
2. Make it rain Turn up the cold and the cloud lets go.
3. Make it snow Turn the heat down and the cold up until the thermometer is below freezing.
4. Make a rainbow Rain and sun at once: pick where to look.
5. Dress for the weather Pick the right clothes for sun, rain and snow.

Big levels (ages 7 to 9)

1. The water cycle Tap sun, vapor, cloud, rain and lake in order.
2. Where does wind come from? Heat the beach and predict which way the breeze blows, by day and by night.
3. Rain or snow? Read the thermometer and predict what falls from the cloud.
4. Make fog Set all four dials to make a cloud that sits on the ground.
5. Thunderstorm Heat, water and cold make a towering cloud; count the seconds to the boom.
6. Forecast Read the dials and predict tomorrow's weather.

The big ideas

• The sun drives the weather. Sunlight warms water until some of it turns into invisible vapor that rises. Up high, cooler air turns the vapor back into tiny drops: a cloud.

• Rain, snow and fog are all the same water. Drops in a cloud grow until they fall. Below freezing they fall as snow. Fog is a cloud that forms right at the ground on cool, calm, damp nights.

• Water goes round in a cycle. Evaporation, condensation, precipitation, and rivers back to the sea. The same water has circled the planet for billions of years.

• Wind is air on the move. Warm air rises and cooler air flows in to replace it. Land warms faster than water by day and cools faster by night, which is why sea breezes turn around after sunset.

• Rainbows and thunder follow simple rules. A rainbow appears only with the sun behind you and rain in front. Lightning's light arrives at once, but its sound takes about three seconds per kilometer.

Try it at home

1. Cloud in a jar Pour a little hot water into a jar, rest a plate of ice on top, and watch a small cloud form where the warm vapor meets the cold.
2. Rainbow with a hose On a sunny day, stand with the sun behind you and spray a fine mist in front of you. Turn around and the rainbow disappears.
3. Count the thunder In a storm, count the seconds between the flash and the boom. Divide by three for the distance in kilometers (or by five for miles).
4. Be the forecaster Each evening, look at the sky and the thermometer and write a forecast for tomorrow. Check it the next day.

Ask after playing

• What did we have to turn up to make a cloud?
• Why did the rain turn into snow?
• Where does the sun have to be for you to see a rainbow?