If you’ve got it, flaunt it!

Thursday 15th July 2021

How much thought do you give to the calculator that your students have? The story goes that it has more processing powers than all of NASA had back in the 1960s when they put a man on the moon (too good of a story to check!)

We all know how to use calculators for the things that we know we need to do, but there could be so much more it can do that you've not tapped into. You may not have an expensive graphical calculator, but even the basic scientific calculators do a lot more than you might realise. I often ask GCSE resit students about ways in which their teachers had taught them how to use their calculator, and many of them didn’t think their teachers ever had!

Here in the West Midlands region, we've been running a professional development event on the effective use of calculators – if you weren’t with us on Wednesday 7 July 2021, it’s not too late to sign up for the second part of the event happening on Tuesday 5 October 2021.

In case you missed the first part, here’s a couple of highlights. Have you played with Shift-SOLVE? The Casio fx991 Classwizz has a SOLVE function in yellow – use the \(x\) key to type the equation \(\frac{1}{(x+2)}=x+4\) using Alpha and the CALC key for the equals sign. Then Press Shift and SOLVE (also the CALC key) and choose a start number for \(x\) (or use the previous value the calculator has stored) and press equals. One root of the equation will show as a decimal. If you want another root, explore different start numbers. If you want exact roots, you’ll have to rewrite the equation as \(x^2-2x-9=0\) and use the equation mode to get surd answers. Comparing the decimal value form one method with the surd answer for the second is a great for checking the algebra done at the rearranging stage – and, to be fair, that's where most of the mistakes are going to be made!

If you want to use the calculator for algebra, try Table mode. For example, you can type in a quadratic for \(f(x)\) and then what you think the factorised or completed square form for \(g(x)\). Whatever settings you pick for the table, if you get 2 columns exactly the same, there’s a fair chance that your algebra is correct. It will work for partial fractions too – notice you should get the same values for which the calculator puts ERROR – you can use this a start of a useful class discussion.

And did you know that if you've done a series of calculations, each of which disappears when you type the new one, that you can scroll up and see the previous ones? Not a lot of people know that!

For our professional development session in October, we’ve got loads of ideas for teaching calculus, statistics and coordinate geometry using scientific calculators lined up – and a quick peek at graphical calculators if people want to see. We hope to see you there!

By Rose Jewell

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