Damn, this site ate my answer so here we go again:
If you study early childhood ed, you will see that many of the ideas presented in common core math actually work for younger minds. The arrays, counting boards and number lines are hands-on, tangible ways for kids to understand numbers and math concepts. I think people have become highly reactionary about common core without understanding what is *good* about it. My son is in second grade and thriving with the Bridges math they teach at his school.
He was home sick today; here's a website his teacher recommends:
http://catalog.mathlearningcenter.org/apps
Kiddo spent about 40 minutes playing with the geoboard application, creating all sorts of fun pictures. There is a lot of room for open-ended play on the apps presented. Just a suggestion; even my luddite self could figure out the functions pretty quickly. Math should be not just numbers but introducing geometry around this time, keep it fun. :)