Friends of 10" to our adding facts games.
I had Katie count out 10 red beans and I used a gold sharpie to color one side of each of them. I had Katie write the words Friends of 10 on the top of the paper. I wrote the words red and gold on the paper. We put the beans in a paper cup and I had Katie shake them and poor them out onto a paper. I had Katie tell me how many red beans there were and how many gold beans there were. For example one time she had 2 red sided beans and 8 gold beans. I asked her what 8 + 2 was and she started to count until I asked her how many beans we started with. Then I asked her again what is 8+2. This time she got it. I played around with it telling her these were magic beans. After a while instead of putting them all back in the cup I just turned one of the beans over. We did 11 different ways of adding to 10 with whole numbers. As we got to ones that were similar like 8+2 and 2+8 I would have her try to figure out the second number without counting, kind of a pre-algebra type of thing, which I think is part of the premise of singapore math.
Another day I printed out the sheets from here. I cut them out and laminated them. Next we played with the various strips showing again the various ways to take two numbers to add up to 10. My three and a half year old even enjoyed this.