Friday, August 16, 2019

Common Errors Made Past Times Maths Teachers

I've late started working with a couplet of trainee maths teachers. It's already proving to hold upwardly a useful sense for me - I'm certain it volition own got a positive behave on on my teaching. It's fascinating to sit down at the dorsum of the classroom with my students. 

There's been a couplet of moments lately where I've seen a trainee instructor tell a flat something that's non quite right, or that I've felt has needed farther clarification. It's interesting to run across how a teacher's plain of written report noesis - especially their noesis of mutual misconceptions - develops rapidly over the kickoff few years of their career.

I've started to push clit together a listing of some of the mistakes or oversights that I've seen both inexperienced together with experienced maths teachers make. I'd hold upwardly interested to listen what you've seen every bit good - delight permit me know therefore I tin create a comprehensive listing that volition hold upwardly of piece of job to trainees together with NQTs. 

Square root
The foursquare rootage symbol denotes solely the positive root. So if you lot write √9 = ±3 on the board, you've made a mistake.
Source: Wikipedia
If you're solving the equation x2 = nine together with then of course of written report in that place are ii solutions - both positive together with negative iii piece of job here. You're non wrong nigh that. But brand certain you lot piece of job the radical sign correctly.
   
Angles
What angle fact is depicted below? Some of my students own got been incorrectly taught to say 'angles inwards a circle amount to 360o'.  It should hold upwardly 'angles unopen to a dot amount to 360o' (as per GCSE grade schemes) or 'angles inwards a total turn/revolution amount to 360o'.

Whilst we're on the plain of written report of angles, I've solely late institute out that proverb 'angles inwards a triangle are supplementary' is wrong. Supplementary way that ii (and solely two) angles amount to 180o.

Prisms
I don't recommend bespeak maths teachers on Twitter whether a cylinder is a prism! I did that in 1 lawsuit - the declaration went on for days together with I was none the wiser every bit a result.
Since this Twitter conversation, I avoid defining a cylinder every bit a prism inwards representative I'm wrong, merely I practise tell my students that nosotros bring out the book of a cylinder inwards the same way nosotros bring out the book of a prism.

Interestingly, the GCSE formula canvas uses a controversial moving-picture present of a prism.
Frustum
It's a frustum, non a frustrum. This give-and-take is ofttimes misspelt.
The guild of operations
Try this question: 3 - 3 x 6 + 2.

If you lot don't acquire an respond of -13 together with then you lot demand to hold off in 1 lawsuit to a greater extent than at the guild of operations. The unhelpful acronym BIDMAS (which incorrectly implies that you lot should add together earlier you lot subtract) confuses some teachers every bit much every bit it confuses students.

Vocabulary
I late observed a lesson on angles inwards polygons with a Year 8 class. The pupil instructor asked the advert of a 7 sided shape together with a man child position upwardly his manus together with said it was a heptagon. The instructor said he was correct, together with then moved on. She didn't notice that some other man child was real bothered past times this. He angrily protested to the students unopen to him. I watched from the back. This man child had been taught that a 7 sided shape is called a septagon - which is also right - together with he idea that the instructor had made a mistake. At kickoff he was angry, merely together with then he doubted himself. His confidence took a knock. Later inwards the lesson, when the chance arose, I reassured him that both price are acceptable. He was relieved. He felt vindicated. It was a shaver oversight past times the instructor merely it had quite an behave on on this student.

I in all likelihood practise things similar this every bit good sometimes. We say things that, rightly or wrongly, differ from what students own got been taught previously. This causes confusion together with mistrust.

I'd hold upwardly interested to know what mistakes together with oversights you've seen teachers make, therefore delight comment below or tweet me therefore I tin push clit together a comprehensive list. We're ever talking nigh the importance of students learning from each other's mistakes, therefore let's practise the same.