Greenhouse Effect
Greenhouse Effect is how trapped air in a closed space warms up faster than open air around it.
A closed glass jar left in the sun traps heat inside its walls. Light passes through the glass, but the warmth cannot escape back out. The air inside the jar gets much hotter than the air just outside it. This is how Earth's air traps the sun's heat close to the ground.
Explaining greenhouse effect by grade level
A greenhouse is a small house made of clear walls. The sun heats the air inside. That warm air cannot leave, so it stays hot. A plant in a greenhouse grows more than one left outside.
Projects that explore greenhouse effect
When you cover one thermometer with a glass jar and set both in direct sunlight, something telling happens. The open thermometer stays close to the starting temperature. The covered one climbs higher each minute, as the jar traps warm air the same way greenhouse gases trap heat around the Earth.
Plastic wrap and straws create a small greenhouse that traps air inside. The trapped air warms up faster than open air. The hypothesis predicts the greenhouse plant will grow larger during the 1-2 week growth period.