Practice in the car. Practice on an airplane. Practice as you go for a walk with your child. Ask your child to explain how they figured out the answer. Use a "million dollar question," and ask...
How do you know?
Are you sure?
Can you tell me more about how you figured that out?
DOUBLES! DOUBLES! I CAN ADD DOUBLES (1-5) song
DOUBLES! DOUBLES! I CAN ADD DOUBLES (6-10) song