Make an estimation jar. Find a jar, vase, or clear plastic up. Have your child fill it with legos, or some other item. Try to guess how many items are in the jar. Count how many are in the jar and see how well you did estimating. Repeat with a different number of items.
Have a counting scavenger hunt. Can you find six shoes? Can you find ten stuffed animals? Can you find three books?
Count and eat. Find something small for snack and practice one to one correspondence by counting out each one. Practice subtracting when eating them.
Practice counting out loud to 35.
Practice writing the numbers 1-10.
Make number flashcards and practice number recognition 1-10.