Over the years we've developed a few math activities that we really enjoy. The key for us is if they can be used in several different ways, by various abilities.
1. Hundred's Chart:
When the kids were 5 and 3 there was a bumper crop of acorns.
We started collecting them for fun, and ended up using them on a hundred chart. We hot glued the acorns and the kids helped me write the numbers. In hindsight I would make the chart 1-100 instead of 0-99, and may do so on the back. The acorns have long since fallen off, but we still use the board for reference, and for homemade board games.
2. Counting Stones: A second favorite is this collection of numbered beach stones. These have been casually collected over the past few summers and numbered with a Sharpie marker-pen. The kids use them for all kinds of activities (number order, evens and odds, skip counting, patterns, sorting, etc). They are also smooth and pleasing just to hold.
3. Sorting Animals: These tiny animals were a gift one year from my sister. Not sure where they came from, but they are perfect for math and other play. We've used them for sorting, adding, multiplication, visual/mental math, and all kinds of pretend play.
4. Corners Cards: One of our new favorites are these cards, which came as a set from "Right Start". They are officially the "corners game" but Wylie has been having fun making up his own games.
We also use our Abacus from Right Start all the time, and it has been really helpful (especially to me) in learning visual/mental math.
Mud: This has nothing to do with math, but the weather was so nice we opted for playing in the mud instead. We realized Kale has never played in mud before. Yeah spring!