To sign ask, hold up the index finger of your dominant hand in front of your body while the rest of the hand is in a fist, then as you move your index forward, transform it into the letter 'X' sign. It is as if you are turning it into a mini question mark as you talk to the child in front of you. You can reverse the direction if you want your toddler to be the one to ask you something.
Teach your child the ask sign in the context of seeking and learning new information.
Teach your child this sign in real-life situations where you are encouraging your toddler to engage in simple conversations.