C.
I am a 4th grade teacher and this is what I show my kids: If you take the times tables and remove the "easy" ones, like the 1s, 2s, 5s, 10s and 11s(except 11 x 11 and 11 x 12), and then take out the ones that are reverse of eachother (like 4 x 5 and 5 x 4) The 9s he can do on his fingers (if he doesn't know that let me know) Anyway, when you take all of those off the times table chart, there are only 24 facts that he would need to work on. 3 x 3, 3 x 4, 3 x 6, 3 x 7, 3 x 8, 3 x 12, 4 x 4, 4 x 6, 4 x 7, 4 x 8, 4 x 12, 6 x 6, 6 x 7, 6 x 8, 6 x 12, 7 x 7, 7 x 8, 7 x 12, 8 x 8, 8 x 12, 9 x 12, 11 x 11, 11 x 12, 12 x 12. You can also go on teachertube.com and look up some of the multiplication rock songs from Schoolhouse Rock. My daughter who is 6 loves those and she is even starting to know some of her times tables. Hope this was helpful!