Calculators

Friday 25 March 2005 at 2:40 pm | In Articles | 3 Comments

eon has brought my attention to Tall, Dark & Mysterious’s post about the use and abuse of graphical calculators which is worth reading.

It mentions the use of calculators on mobile phones etc, but I don’t allow their use in maths classes because they give the wrong answer (try 1+2 \times 3 on them or on the Windows standard calculator and you’ll see what I mean).

The new A level syllabuses don’t distinguish between scientific and graphical calculators, but both are banned from the first Pure Maths module. It will be fascinating to see how students cope with this.

My Norwegian students all have graphical calculators (mainly Casio which I find difficult to use compared with Texas, though I like Casio’s scientific calculators) and the only way they are able to solve quadratic equations is to use the calculator, even if the quadratic factorises easily.

Other students, being students, don’t always bring calculators even when they need them. So when they have to solve \sin\left(3x+45^{\circ}\right)=0.7,\  -90^{\circ} \leq x \leq 90^{\circ} I am very tempted to give them old-fashioned four-figure tables (which you can still buy!) but instead I give them an old scientific calculator. On those, to find \sin 30, you have to type 30 \sin which so flummoxes them that they don’t forget to bring their own calculator again :D

3 Comments »

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  1. I think I’d rather use the four figure table!

    Comment by Sam Raskin — Saturday 26 March 2005 4:27 am #

  2. Strangest thing. The standard Windows calculator gives 9 for 1 2×3 while the scientific mode gives the right answer 7!! How hard would it be to assign the same algorithm to both modes?! Son’t bother to answer. Of course it Windows!

    Comment by swimmer — Monday 11 April 2005 2:29 am #

  3. I am fully for permitting NO calculators in math exams, unless it is a numerical methods class.

    Being the slide-rule breed, I do like the ‘old-style’ calculators on which I enter the ‘argument’ before the function. This way, as in the slide rule, I can see and check the intermediate results, and sometime change the course of the calculation (like an if-then-else construct) depending on the outcome. It is hard to find those these days.

    For Swimmer: the ‘incorrect’ mode is for people used to the first generation of calculators that came out in the 1970’s where there was not enough memory to handle the algebraic, and much less, the RPN notations.

    Comment by PC — Friday 3 June 2005 2:00 pm #

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