Why

Why is signed by taking your dominant hand and making the ASL sign for the letter 'Y' at the side of your head. A variant of this sign is to wiggle your middle finger up and down with the rest of your fingers spread out, palm facing the side of your head. A third alternative is still to make the letter 'Y', but after pulling your hand a bit further down your dominant side.

Whichever sign you use, make sure you furrow your brow to signal to your toddler that you are asking a question.