What is the missing first step of the following process: - A muscle fiber gets a signal from its nerve - Proteins and chemicals release energy to either contract the muscle or relax it - When the muscles contracts the bones connected to he muscle are pulled closer together - When the muscle relaxes the bones move farther apart.
Ans: Muscles work by expanding and contracting

What is the missing first step of the following process: - The caterpillar eats constantly until it grows bigger - The caterpillar starts to form a cocoon around itself - The caterpillar becomes a pupa - After some time the cocoon hatches - And a butterfly is born.
Ans: A larva is born

What is the missing first step of the following process: - Miners enter the mine - Miners remove the coal from the mine - The coal is placed into carts or on a conveyor belt - The coal is moved up to the surface - The coal is loaded onto a truck - The truck takes the coal to a power station.
Ans: A mine is excavated in the side of a mountain

What is the missing first step of the following process: - The plants and floor absorb the the sunlight - The absorbed sunlight is converted to heat - The heat cannot escape the glass - The heat is trapped in the greenhouse - The hot air rises - The colder air at the top is pushed to the bottom - The colder air is then warmed by the floor and the plants.
Ans: Sunlight passes through the glass into the greenhouse