Problem: What is the missing first step of the following process: - The female lays eggs - The eggs are incubated by the parents, by sitting on them, for weeks - The bird hatches from an egg - The parents feed them as the continue to grow - Develop flight feathers - The parents teach them to fly - After learning to fly they leave the nest to live on their own - The next year they breed beginning the cycle again -

A: A male and female bird mate

Problem: What is the missing first step of the following process: - The atoms become unstable - The atoms split - In alpha decay, two protons and two neutrons are released from the atom - In beta decay, a neutron changes into a proton and an electron - The proton joins the nucleus of the atom - The electron is released -

A: The nuclei of some atoms have too few or too many neutrons

Problem: What is the missing first step of the following process: - The cracks get very long and big in some places - The earth places pressure against the rocks on both sides of the cracks - The pressure causes the rocks to press against each other very hard - The cracks continue to develop - The earth moves against itself on both sides of the cracks - The pressure and movement around the cracks causes the rocks to crumble in some places - A lot of energy is released - The energy causes seismic waves - The seismic waves move the earth in an earthquake.

A: The earth develops cracks deep beneath the surface

Problem: What is the missing first step of the following process: - The star does not have enough mass to become a neutron star - The star goes through a change in its core and bonds helium to carbon and oxygen - The star becomes a red giant - A mass of carbon and oxygen builds up in the center of the star - The star sheds its outside layers and becomes a nebula - The star leaves behind the core which becomes a dwarf star.

A:
A star forms