As long-term readers know, I have not been consistently Montessori with my son and have leaned toward unschooling. While I've presented different things to him over the years for working on multiplication, he has not had any real interest and I was never consistent enough to get him to a point of really mastering his tables.
In enters this last part of the school year and my insistence that he do some sort of regular math and felt that something more structured would work better with him--he can use the school text or he can use Life of Fred--Fractions. (I was also thinking I could just give him Ray's Arithmetic if he really protested to those two.) He chose Life of Fred.
Well, he's gotten to parts where he needs to use the lowest common denominator. And I have basically told him to each time write out the multiples of his denominators to find the common denominator. He is getting faster and faster at it and I'm noticing he is remembering more easily certain facts, like just now, 7x3, he knew immediately was 21. :)
It's a bit of a rough go having him work on fractions when he doesn't know his multiplication tables, but he knows I am insisting that he will keep working on this book until he's done, even if it's during the summer, so he is pretty willing each day to work on a lesson.