Skip counting by 3s

Skip counting is nothing more then a precursor to multiplication as long as you make it a little bit fun your children will learn it.
3:
3, 6, 9,
12, 15, 18,
21, 24, 27,
30, 33, 36, 39,
42, 45, 48,
51, 54, 57,
60, 63, 66, 69,
72, 75, 78,
81, 84, 87,
90, 93, 96, 99