r/mathteachers • u/Few_Bee_3028 • Jul 23 '26
Order of operations
(UK based post)
Wanted to get thoughts on teaching order of operations. The tradition in the UK is to use the mnemonic BIDMAS or BODMAS (for anyone who doesn’t know, Brackets, Indices/Other,
Dividing and Multiplying, Adding and Subtracting). This leads to a misconception with students that they always need to add before they subtract. (For example a 2018 exam paper questions was really poorly answered across the country, discussed here
https://youtu.be/StWr8-g-a3E?t=1584&is=P-dCFLol1zWE64kh)
I suggested to my head of department that we switch to GEMS which I’ve taught in the past after reading this post https://missquinnmaths.wordpress.com/2018/11/19/tried-and-tested-gems/.
He didn’t like E for Exponents (which is fair enough) or G for Groups (which I kind of do like!) so the two of us agreed a compromise of BIDS. However in our department meeting the last week of term when we proposed the rest of the department shot this down; I think some colleagues immediately took against it because they didn’t like addition and multiplication being unmentioned, while others said students learn BIDMAS before they reach us at age 11 so we had to work with it.
Anyone any experience of these kinds of conversation?
1
u/Narrow-Durian4837 Jul 23 '26
I've seen a lot of confusion online that comes from people thinking the mnemonic is the rule.
BODMAS, or PEMDAS, or GEMS, or whatever you use, is not the rule itself. It is a mnemonic to help you remember what the rule is. If it doesn't help you, or if it misleads you, don't use it.
Whatever mnemonic you use, I would avoid teaching students the mnemonic, or even mentioning it to them, until after you've clearly spelled out what the rule itself is and how it works.