Play the missing number game. Order numbers 0 to 20, then get your child to close their eyes. Cover any number and then ask your child which is missing. See if they can explain how they know? e.g. 13 is missing because it is one more than 12. They children love this game at school, it is fast pace but great for showing their understanding of number.
Find a wall your adults don't mind you marking on (outside brick wall), ask a sibling or adult to mark on the wall how tall you are and then write your name next to the wall. Do this with your siblings and adults at home. Then place your family in height order from shortest to tallest, talk about this using this language.
What else can you measure by height? Why not try by length?