# Fracture form of rational numbers

Els Coussement shared this problem 4 years ago
New

We hope that a lot of schools in Flanders will replace the graphical calculator (Texas Instruments TI 84, Casio) by apps of GeoGebra, such like the GeoGebra Graphing Calculator. At the moment we are missing something in this app of GeoGebra. The pupils use a lot the function ‘Fraction’ on their TI-84 to write a rational number in fracture form (for example: 0,125 becomes 1/8). I don’t find how you can do this in the GeoGebra Graphing Calculator. I even think that no such function is implemented in this app. Is it possible to add this function to the app?

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In my opinion (as a math teacher) this is not an issue of geogebra. You should teach you pupils to do it (convert a rational number in fraction form) themself.

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fractiontext works for me

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@Jozef Dobos

Yes, the command exists already. But it's only implemented in CAS, not in apps like GeoGebra Graphing Calculator and GeoGebra Scientific Calculator. In the apps for mobile phones, I think that you can't switch with your results to another app.

Els

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I used graphing for my screenshoot in very very old smartphone

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My smartphone is old too, but online version of geogebra is working on it.

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@ mathmagic

But you got the result with the command fractiontext, not with the command rationalise. The result is text. When a pupil gives two points, for example A(0,2) and B(3,3), and then draws the line AB, he don't want to see the equation y=0.3333333333x+2 but y= 1/3 x + 2 in the algebra window.

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@Joze Dobos

I suppose you work then with the online version of GeoGebra Classic on your smartphone? Then you need wifi. Not all pupils at school can use wifi, certainly not in exams. And for some pupils the classic version of GeoGebra with CAS is rather complex to use.

I think that our teachers are more interested in the offline apps like the GeoGebra Scientific Calculator and the GeoGebra Graphing Calculator to replace calculators like the Texas Instruments TI-84. GeoGebra Classic is more suitable to projecting an applet with a beamer or to let pupils work on computers.

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Yes, fractiontext works. But it is text. You can't use it to calculate.

In fact, I would like the function 'fraction' of the TI 84 not only in the GeoGebra Graphing Calculator but also in the GeoGebra Scientific Calculator.

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@AbacusWhat to include in a calculator and what not it's an interesting discussion. In fact you can think about a lot of things in any calculator (GeoGebra or other) pupils should be able to calculate themselves. Ommiting all of them would leave little. But if you introduce them you can include features that are more than handy because you can spend time on reasoning on math that you don't have to spend on just calculating techniques. This is what a calculator is about, no?

chris

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This is an interesting subject indeed.

As far as I know, TI 84 is able to convert numbers in fractional form using Math->Frac menu, even if viewing fractions in the input screen is sometimes a bit cumbersome.

As far as I can remember, entering a function in the Graph screen doesn’t show the coefficients in fraction form.

One of my students is currently using a Casio (No graphics, no CAS) that displays fractions much nicely, as well as exact values of outputs of sine and cosine for main angles. This is nice from a certain point of view - it’s great to see cos(30°)= sqrt(3)/2, but this way kids don’t learn the main trig values, and this is a thing that I want from them.

I definitely agree with Chris about the use of calculators meant to simplify the calculation bit in order to keep students focusing on how to solve a problem, and having a nice interface that displays the result in fractional form is definitely a plus for me.

I prefer to work always with exact values, and imho the same should be taught to kids, because most of the time they are not aware of how approximate values can generate big errors.

Using a calculator that computes and displays fractions it totally bad for middle schools, instead. Because they need to learn how to deal with fractions.

Of course I expect the main user of ggb as an high school student, so in this case fractional forms are welcome

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@Simona Riva

You understand very well what I have in mind. Of course, we have to learn our pupils to calculate themselves. Calculate every operation with a calculator, is not the best way to teach mathematics. Therefore there will be in future still tests or exams where a calculator is not allowed. But for some more difficult problems, calculators and GeoGebra can be useful. You have more time to focus on the real target of your lesson. GeoGebra can also be useful for pupils to control their own calculations.