If we were to propose a math activity for a small group of 2nd grade children, we would teach them to add and subtract from 20 by using bags of skittles. Each child would start with 20 skittles of different colors. We would first have the children count and remove all of their purple skittles from their desk. After removing the purple skittles we would have the children count how many skittles remained in their pile. This concept would teach them that subtracting, say, 7 purple skittles from a pile of 20 skittles would leave them with 13 skittles. Afterwards, we would have the children put the purple skittles back into their pile. We would then have half of the children remove all of the orange skittles from their neighbor and put them into their own pile. This would teach the children that adding, say, 5 orange skittles into a pile that started with 20 skittles would give them 25 skittles. At the same time, the children that had 5 orange skittles removed from their pile would see that removing 5 orange skittles from their pile of 20 skittles would leave them with 15 skittles. We would then have the children switch so that the children who hadn’t practiced with addition yet would get to add skittles into their pile. We would continue this activity with different skittle colors until the children were able to predict the change to the number of skittles in their pile before actually adding or removing any skittles from it. Each time the children were able to accurately predict a change without physically seeing any added or removed skittles, they would get to eat a skittle from their pile.