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Core Maths Revision – Questions I wasn’t expecting

January 12, 2020

My students have a mock exam this week so we’ve spent some time revising. There were a few questions that came up that I wasn’t really expecting and I wondered if these are the sorts of things that come up in other core maths classes too. I’ve added my thoughts and/or answers as appropriate.

How do I do XYZ on my calculator?

My (internal) response is “How can you not know that!?!?”. Obviously, I show them again but I don’t really know how to make it stick. I have made some calculator drill resources (find them here) which is designed just to help with learning what buttons to press but I can’t help but think this is really down to the student to learn!

What’s r again?

This one again falls into the “how don’t you know that?” category but I’m beginning to wonder if there actually is a lot of new vocabulary and facts to learn. The very same students will then later ask me, “what’s the product moment correlation coefficient again?” even after I’ve told them that r is the correlation coefficient. This obviously suggests that it didn’t stick in their head the first time (and they haven’t revised independently). I’ll need to do something about planning for revision for the real exams.

When you’re numbering the list of data for a random sample, do you number across or down?

That’s quite a nice question and while to us, it’s probably obvious that it doesn’t matter, it’s good to reminded not to take these things for granted. I asked the student if they thought it would matter and they said “no” after thinking for a moment but I wonder if the fact that I asked that question implied that it didn’t.

If I just wave my hand over the page and stab downwards, how is that not random?

Quite hard to clearly argue this one but I went with the fact that you tend to stab near the middle of the grid (they annoying hadn’t though). I also pointed out that if you knew you’d stabbed near the top left, you’d probably avoid that again too much which isn’t random. I’m not sure how convinced they were.

How do I know when to use frequency density and when to use cumulative freq?

Well, cumulative frequency is for cumulative frequency diagrams. You’ll just have to learn that histograms are the one that use frequency density – nothing else does!

What’s the correlation coefficient again?


One Comment
  1. Kate Smart permalink

    I totally sympathise with the r thing. I think it can be confusing…..and PMCC as well

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