Bigger traces the growth of a boy from way back before he was born (the text "Once I was very small. I was so small that I was hardly even me." accompanies a small illustration of a baby in his mother's womb) through his childhood. As he grows, the boy gets bigger and at each stage he is able to do things he wasn't able to do before. Before long he can see above tabletops, reach doorknobs and telephones, and touch the light switch on the wall (even though he is not supposed to). All the while he keeps getting bigger, and so does the world around him.