I teach in a resource room. The lattice method of multiplication can be very successful for children (and adults) who just can't get it the traditional way. My brother is a prime example. He has a learning disability in math (discalculia, I probably spelled that wrong). He absolutely can not multiply correctly the traditional way. I showed him the lattice method and he caught right on. The bottom line is that there is more than one way to skin a cat. I teach both ways and make sure the students understand it either way. Then they are free to choose whatever way works for them. Keep practicing so he can do it either way -- as long as he is correct, quick, confident and understands the concept, the method doesn't really matter.