At about 15 months old, ask your child to stack 2-3 blocks, perhaps with help. By 18 months, your toddler can build a tower of 3 blocks without help. By 24 months, your toddler could build a tower of 6-7 blocks. As your child gets older, they can add more blocks, often with one hand. Applaud your child when they place the last block on top. Knocking it down is fun too! Don’t forget to count the blocks and talk about their colors.