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Calculator Use: Probing Questions

Whether you are looking for a question to stimulate discussion in lesson, or a challenge at the end of a homework, then hopefully you will find these useful.

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Convince Me That... keyboard_arrow_up

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I use Convince Me That questions lots in my lessons and homeworks. Providing students with a statement and challenging them to come up with as many different ways of convincing you as possible can lead to some fascinating discussions. The different ways of seeing the same thing can also help improve the depth of students’ understanding. Thanks so much to the Thornleigh Maths Department, in particular Erica Richards, Anton Lewis and Gareth Fairclough for helping me put these together, and we will endeavour to keep adding more!

If I am solving the equation $2x^2-3x-5$ and I type in $-(-3)\pm \frac{\sqrt{-3^2-4\left(2\right)(-5)}}{2\left(2\right)}$ convince me why I will not get the correct answers.

Convince me that $-3^2$ typed into a calculator will give -9.

I am working out an angle in a right-angles triangle, and I type in ${\cos }^{-1}\left(\frac{5}{3}\right)$. Convince me that this will give “math error” without typing it in.

When I type in $2+3\times 4$ I get 14

VI3 Treatment keyboard_arrow_up

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We devised VI3 Treatment as a versatile way of giving students meaningful follow-up work at once we have marked their homework. The idea is that students are challenged to come up with 3 things with certain constraints. These are ideal to use as an extension for students who have got everything correct, and also as further purposeful practise for students who have got a particular question wrong. Use the ideas below and adapt them accordingly, using different numbers where appropriate. Either mark them yourself or better still, get other students to do it. Thanks so much to the Thornleigh Maths Department, in particular Erica Richards, Anton Lewis and Gareth Fairclough for helping me put these together, and we will endeavour to keep adding more!

Give me three ways of getting a number equivalent to $2\frac{3}{4}$onto my calculator screen.

Find three ways of getting a “math error” on your calculator!

Find 3 interesting buttons on your calculator and write down what they do