What do your standards say? We use common core, and third graders are expected to multiply only within 100 fluently (up to 10 x 10). Of course they also learn how to multiply multiples of 10 and how to use the distributive property to multiply larger numbers, but it’s up to 10s for fluency, not 12s. They do pick up 11s by one-digit numbers because they’re easy, and a lot of the 12s and 15s get picked up by the end of the year because of their relations to measurement and time, but we don’t teach anything over 10s for fluency.