What is it when you put shampoo on your hair and then you _______ to create foam?
with your fingertips.
Add water?
http://womenshair.about.com/od/shampoo/a/how2shampoo.htm
Read the second paragraph carefully.
Lather?
To create foam when you put shampoo on your hair, you typically do one of the following actions:
1. **Rub**: Rub your palms together to create lather, and then apply and distribute the shampoo evenly through your hair.
2. **Massage**: Gently massage the shampoo onto your scalp using your fingertips in a circular motion. This action helps to cleanse the scalp and stimulate blood circulation.
3. **Agitate**: Move your hands back and forth or up and down vigorously while applying the shampoo to produce foamy bubbles.
By performing any of these actions, you create friction, agitating the shampoo and air in the process, which then traps air and creates bubbles resulting in foam.