Emulating the TI-84

American schools have been using Texas Instruments calculators for more than a quarter of a century now. They have become the de facto standard. More recently, computers and projectors have become ubiquitous, so you would think that we would have a better solution for demonstrating calculator usage to a class. Pointing to a poster or giving oral instructions can be of limited use (at best), as students have to be following along and not get lost. For example, consider this daunting sequence of instructions:

  1. Press the STAT button.
  2. Press Edit from the EDIT menu.
  3. Enter your data in two columns of your choice. For example, use L3 for the independent variable and L4 for the dependent variable.
  4. Press 2nd-QUIT to return to the home screen.
  5. Press the STAT button.
  6. Go to the CALC menu and choose the fifth item, QuadReg.
  7. Type L3 (which you get by pressing 2nd-3), then a comma (which is located above the 7 key, of course), then L4 (2nd-4), then another comma. Don’t press ENTER yet!
  8. Press the VARS button, the go to the Y-VARS menu, and choose 1 (Function). Press ENTER now.
  9. From the FUNCTION menu, choose Y6 (or wherever you want to put your regression equation).
  10. Now you’ll be back on the home screen. Press ENTER.
  11. If all has gone well, you’ll see a general quadratic equation in standard form, along with values for a, b, and c; and you’ll see the coefficient of determination, R2.
  12. If you press the Y= button, you’ll see…

I’m not done yet! But you get the idea. We actually expect students to learn this complicated process.

Needless to say, they’re not going to learn it unless two requirements are met: meaning and practice. They have to understand that each step has a mathematical meaning; it’s not arbitrary. They have to practice the whole procedure several times, so that it becomes second nature.

How do we help students meet these two requirements? Unless we can sit down with a student one-on-one (which is sometimes necessary), we need to demonstrate it to the class. One way to do this is to download the free Virtual TI emulator from ticalc.org, which is perfectly legal as long as you have already bought an actual calculator of the same model that you are emulating. This program works very well, although it’s Windows-only and therefore requires Mac users to run it under Parallels or the like (or to run it on a PC and use Citrix, which works fine). The downside is that the emulation is too perfect, showing exactly what you see on a real calculator in real time. At any moment, you get a snapshot of what’s happening right now, and only that snapshot.

So a second solution is to use a real calculator under a document camera — if, of course, you have a document camera. This solution is almost identical in its effect, with the minor flaw that your fingers can get in the way, and the somewhat more major flaw that a lesson spread out over two days can be disrupted by other use of the calculator in the meantime. This other use can change or delete your stored data, whereas someone else’s use of the Virtual TI is less risky as they probably have a different copy.

A third solution is to use the official TI-SmartView software from TI. This too is free…for 90 days. Its great advantages are that it displays several representations at once (multiple representations being one of our Big Ideas) and that it shows a history of key presses:

 

TI SmartView screen shot

 

I’m currently trying solution #3, which strikes me as the best (aside from the 90-day limitation, of course).



Categories: Math, Teaching & Learning