Here is the land below a volcano before it erupts: a green field, three trees and a road.

Before: a quiet volcano, a green field, three trees and a road.

Now melted rock comes out of the opening. When that happens, we say the volcano erupts.

Lava pours out of the opening.

Lava is a liquid, so it flows downhill.

It flows over the grass, over the trees and over the road.

During: red-hot lava runs down the volcano and across the field.

Lava is so hot that the grass and the trees burn as it reaches them.