Questions from a 3 year old

I was snuggling Greta tonight and she asked me "Why we have air?" I explained breathing, then she asked if plants need air. It is fun to watch her curious mind at work. She also asked about bones and food. I explained and then she wanted to know why her big sister could color so well. It must be hard to be little and never be quite as far along. I showed her how her ears didn't have any bones and could move. She wanted to know why ears can hear? I told her so she could hear me say "I love her." Her smile was a perfect way to end the day.