Calculators

Can I just say I hate, hate, hate TI calculators?

I dislike calculators in general because the students don’t know how to interpret the results it gives.

Ex: Student – “Mr. Bennage, can you help me? I’ve done this problem 5 times and my calculator gave me 5 different answers.”

Me – “Well, show me what you are trying to do.”

Student shows me a formula with numbers plugged in.

Me – “Okay. Now show me how you did that on your calculator.”

Student punches in some numbers and operators with lots of parentheses – gets a 6th answer.

Student – “I’m not sure what I did. Can you just tell me what I need to push?”

Even better example that I dislike:

Student needs to add simple fractions. Uses calculator. Why?

But, why I hate the TI calculators:

4 BIG reasons.

1) Orders of operation. Yes, they should need to know and be able to apply them to do calculations. But, I’ll admit myself that I overuse parentheses on a TI to make sure I enter it correctly. I (rightly so) get the correct answer when I do it. Students invariably get 6 answers like in my first example.

2) Negative signs. Goes along with number 1, but students don’t connect them. Student needs to do -3^2 They usually give the answer as -9. “I punched it in like it is written.” Ugh!

3 and 4 go hand-in-hand also

3) Reciprocals. The TI uses x1 notation. Students have no idea what it means or how to use it. Despite the fact that I went over it 20 times.

4) Inverse trig functions. Again, the TI uses sin1 notation. Looks the same. “Don’t I just use it when I want to flip it upside down?”  (cosecant -after they finally know what reciprocal does).

Obviously there is some teaching I’ve missed messed up. But, why can’t TI get it right like an HP?

I love my HP 48G. RPN is the only way to go as far as I’m concerned. And, for science class, I can use the stack to keep numbers from previous calculations without copying them down or putting them in memory for accuracy’s sake.

HP’s inverse/reciprocal notation, RPN, and text book orders of operation process make the 4 reasons go away. I don’t have any of those issues using an HP.

1/x makes more sense. asin can mean anti-sin (reverse the function). I can enter -3^2 and get 9. I never (almost) use parentheses and my calculation is correct.

Here are the screen shots of the 2 calculators:

Did I mention I hate TI calculators? Too bad every textbook publisher uses them with keystroke guides these days.

Just my soap box for the day. Anyone have advice?

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2 Responses to Calculators

  1. No advice, but I’ll add one more rant:
    Students entering numbers in scientific notion as
    6.02*10^23
    instead of
    6.02E23
    which another place for error.

    Why does the EE key have to be a 2ND function? It deserves its own button.

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