Angle facts- getting the language right

Supplementary angles add up to 180 degrees and...

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How many times have you marked a GCSE paper which is a two-pointer where the question asks “find the size of angle x” and then “explain how you worked this out” to find that the pupil got the size of the angle correct but wrote an explanation that didn’t get the second mark? You kind of knew what they meant in their explanation, but the mark scheme was looking for “interior angles in parallel lines are supplementary” rather than “the angles next to the lines add up to 180”.

Here’s a very simple worksheet that I made to teach a lesson on using the correct language to describe angle facts. The idea is that you run through them with the pupils filling in the explanations on the worksheet which they can then use as a reference sheet when attempting questions later in the lesson.

I found a great way to start this lesson off is to ask the pupils to solve a typical angle fact question with an explanation of how they worked out the angle. The plenary is then exactly the same question followed by them comparing their answer at the end of the lesson with the answer they wrote in the starter to see how much they learned during the lesson.

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2 Responses

  1. Ceejaypee says:


    Currently teach C/D borderline students and nowhere is this more evident that they know what they are talking about but dont give good reasons than on these questions.

    Students also get 180 and 360 confused at times so I will use this by firstly making them write down what “magic” angle number is at work and then why!!


  2. Thanks for this. I’m going to spend some of my time over Thanksgiving break making a ‘So you don’t like your grade in Geometry…show me what you know’ project. This is a great resource.

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