Thank you to everyone who offered advice regarding Me Too and the teen boards yesterday! If you didn't read that post, Me Too was putting the unit cards into the teen boards upside-down pretty often and sometimes over the one instead of the zero but could identify the numbers (even upside down), order the numbers, and match them successfully with bead bars. I theorized that this was all a by-product of the shortness of his arms and the length of the material. He was often sitting on the side of the material and losing track of top and bottom.
As advised, I used a different material (with no size issues) to check his understanding. As soon as I laid out all of the unit cards in front of him I realized that it wasn't a good way to check...he was likely to put the units on the tens in whatever orientation I originally presented. So, I put them all sideways to see what he would do. Sure enough, he was able to build and identify ANY teen I asked for. AND he always put the unit card on the zero and rotated them to be right-side-up! Way to go Me Too!
So, today we were able to move on to the ten boards and he was brilliant :) Thank you for all the advice. This is the type of thing where my perfectionism might have led me to keep him stuck on the teens boards until his arms grew!