Nines seem to pose a bit of a problem for a lot of students but actually it's one of the easiest times tables because there are so many "tricks" you can use to count and multiply by nines.
Here is another video showing yet another way to do it...there are more ways. Here is counting by nines with younger students.
There is a way to use your fingers too. I have to make a short vid on that one too...meantime here is a short post on a simple way to count rapidly by nines.
MB: How is memorizing an algorithm any more fun? Still memorizing. Isn't more helpful to understand why it works? #mathchat
ReplyDeleteCR: why does it work...? You use an algorithm ONCE for all the facts as opposed to memorizing 9 facts, same with using addends.
CR: Further: note the reaction of the student. You'll get this reaction almost every time because it's EASIER. EZ=FUN
MB: Agree algorithm is more efficient, but more fun? Use a hundred grid to develop algorithm-difference btwn 9 & 10 key #mathchat
CR: Check my website & blog I'm all about WHY. However, why not always important to all students, let them figure out why #mathchat
MB: Student seemed surprised. It's a neat pattern not magic & I'd want to use that wonder to explore why. #mathchat
CR: btw one of my sayings is "it's not magic, it's math" check out vids on the why of cross multiplication for example #mathchat
MB: I've had a bit of a look at your website & blog, just was curious b/c student seemed 'hooked' to find out why #mathchat
Twitter my leaste favorite and the most gawdawful way to communicate...