I must first dedicate this post to my mom. She first introduced me to mental math when I was in elementary school. As I tell my students, I used to have to do a series of mental math before I was allowed to eat dinner every night…I’m not sure that’s a true story, but it’s what I like to remember (and I like to tell my kids so they get a glimpse into my math loving family). So, in celebration of my mom, Monday warm ups in my class are dedicated to mental math. In fact, last year, my mom and I had a competition between my students and hers…unfortunately Skype didn’t work the day we planned for, so we did the competition separately…I think we should try again this year, what do you say, mom?! Rematch, 2016??
Anyways, I love doing mental math as a warm up and my students actually do, too. Ironically, when first introducing the idea to my students, there was a whole lot of whining…”Awww no calculators…no, I can’t do math in my head…but, it’s Monday.” So, after a little convincing that everything is going to be okay, my kids soon realized that they loved mental math more than they ever thought! As it creates a little friendly competition amongst each other and themselves, it also reinforces concepts like square roots and any other operations students have been studying, helps students grow their quick thinking algebraic skills, and reinforces their listening skills.
Here’s how it works…ask students to clear off their desks…it’s all done in their heads and the less distractions the better. Tell students not to talk, not to say things like “wait, wait” or “ahh I lost it” (they will do that), because it’s all about listening and processing. Tell students when you are done, and only then, to raise their hands if they got the answer (mine tend to just blurt it out at the end which is okay sometimes, too, if you can’t control the excitement!) Call out a series of operations starting with a single number. I just make it up as I go and calculate in my head as I say it, but you can create the series if you want before and read it off.
Example: take the number 25, add 5, divide by 3, double it, divide by 4, add 2, square it, add 3, subtract 10, divide by 2, subtract 1.
You can get more or less complicated…throw in fractions, negatives, triple digits, ect. Today, I had my kids make up their own problems, ensuring they had operations that could be calculated in their heads and nothing ended with something like 157 divided by 17. Then, I read a few of them out, and in some classes, several students volunteered to try calling the ones they created out to the class.
If you try it, have fun with it…kids get really into it as they race to get them all correct!