Q: 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.
A: Muscles work by expanding and contracting

Q: What is the missing first step of the following process: - The water tank over the boiler is heated - Creates steam - The steam is funneled to the piston - Piston uses the steam as energy - The piston causes the crankshaft to move.
A: Coal is heated in the boiler

Q: What is the missing first step of the following process: - Through erosion, the stream cuts into the soil and bedrock - Through continuous erosion, a deep gash is cut through - After many years the river may dry up - A dry ravine is left -
A: A stream or river must occur

Q: What is the missing first step of the following process: - The trees and plants burn - The animals lose their homes - If the animals can not escape, they may die from smoke inhalation - The plants that provide food are gone - The animals have little to eat -
A:
A forest fire starts