Dip your finger in the water. Use your finger to put one drop of water on a section of the wrapper. Dip your finger in the water again and put a drop of water on another section of the wrapper. Your hair is straight, wavy, or curly because of the shape of its cross section. A cross section of a strand of straight hair shows that it has a rounded shape.
Curly hair has a flatter cross section than straight hair.
This is because parts of a strand of hair absorb water and get fatter, making it twist and bend in different directions. When this happens, some curly hair gets straighter, other curly hair gets curlier, and even straight hair can get a bit curly. Like a strand of hair exposed to moisture, parts of the paper that absorb water get fatter and push on other parts of the paper. This causes the paper to twist and bend similarly to the way a strand of hair curls or straightens when exposed to moisture. Literature Connections Robins, Joan.