Multiplication Flash Cards

I have to write this down so I don't forget and I can reflect upon it later.

Students are in study hall right now. I passed out some multiplication flash cards for the students to work on. One students held two up together: 10 x 3 and 10 x 7. Another student said that make 100. His reasoning was that 10 x 3 = 30, 10 x 7 = 70 and 30 + 70 = 100. I would like to explore the insight of his reasoning. Maybe I'll ask him later about it.

Also, these 5th graders like the sense of being on a team (mine being UCSD).
Also also, some students are making games out of the flash cards.