Problem: What is the missing first step of the following process: - Your diaphragm moves down - Your lungs have more room - Your lungs fill with air - You exhale - Your diaphragm moves back up - Carbon dioxide is exhaled - You start the process over again.

A: You inhale

Problem: What is the missing first step of the following process: - The waves contain sediment from the ocean - The water and particles in it hit rocks and sand on the beach - The wind and current sometimes push the water and particles harder - Tiny parts of the rocks on the shore come off the larger rocks - The waves pick up sand and small rocks from the beach - The waves go back out into the ocean - The waves carry the new particles with them - Rocks and the beach look a little different.

A: Water from the ocean washes onto beaches in waves

Problem: What is the missing first step of the following process: - Partake in activities - Bring out the cake - Sing 'Happy Birthday!' - Blow out the candles - Eat the cake - Open the presents -

A: Begin the party

Problem: What is the missing first step of the following process: - Is exposed to air - A chemical reaction occurs - The iron starts to oxidize - The iron starts to rust.

A:
Iron is exposed to oxygen