Greetings! Within the Mobile Learning group there are iPad Apps suggested. One is Motion Math: Hungry Fish | Motion Math - Play with numbers!. Take a look and see if it would be good for your nephew.
I found another app that you may like. It is called, SlateMath for Kids and is available free in the iTunes store. There are 38 activities that help kids in K-1.
Hi! Today I came across a blog post Apps We Use In Kindergarten (2013 Update) | mattBgomez. I thought of you and perhaps there are a few here you can share for your nephew.
Just a thought for you and anyone esle in this discussion. Smart Apps For Kids is a terrific site with apps for all ages and skills. You can subscribe to daily or weekly alerts for free, discounted, or new apps. I love it and have gotten a lot of ideas from it for all my students!