Problem: What is the missing first step of the following process:  -  The magma cools - Particles inside the magma move closer together - Crystals are formed - The crystals contain minerals.

A: Magma comes up to the surface of the earth


Problem: What is the missing first step of the following process:  -  Slide out the bottom rack - Take a dirty plate - Rinse the plate - Place the dish in the rack - Repeat leaving enough space for water to reach all items - Fill the soap cup - Turn on the dishwasher.

A: Open the Dishwasher


Problem: What is the missing first step of the following process:  -  Engines produce carbon dioxide - Living things produce waste - Waste decomposes - Decomposition produces methane - Water evaporates - Water vapor joins the atmosphere - Carbon dioxide, water vapor and methane are greenhouse gases -

A: People breathe and expel carbon dioxide


Problem: What is the missing first step of the following process:  -  Bloodstream - Cells in the body are attacked - Cells are killed - Different kinds of sickness are formed.

A:
Bacteria enters the body