# Graphing calculators for LHS students

Here is some information on the Texas Instruments graphing calculators in the TI-83/TI-84 series that Lexington High School recommends at least through the class of 2024. (By recommends they mean you will not be able to complete some classwork, homework and tests without one!) Information on this page is correct to the best of my knowledge, but please visit the LHS Math Dept page for the official word.

Acceptable calculators include (roughly in order from cheapest to most expensive; some are discontinued and only available used):

• TI-83 series
• TI-83
• TI-83 Plus
• TI-83 Plus Silver Edition
• TI-84 series (the major improvement over the TI-83 is the USB connector, helpful if you want to transfer files to/from a computer without a proprietary cable)
• TI-84
• TI-84 Plus
• TI-84 Plus Silver Edition
• Color models: The TI-84C and TI-84CE have a color, higher resolution screen and use rechargeable batteries. The batteries are reported to last roughly a week. Today's students are adept with rechargeable batteries, but not always reliable, so keep that in mind, especially since these calculators are often needed on (ahem) tests. The other calculators in this series use AAA batteries which can last roughly a year. The CE is slimmer and lighter, which should make it easier to carry.
• TI-84 Plus C Silver Edition
• TI-84 Plus CE

If price were no object, I'd go for the TI-84 Plus CE unless I were concerned about kids forgetting to keep it charged, in which case I'd go for the TI-84 Plus Silver Edition. Often these are available for a much lower price during back-to-school sales. But really any of the TI-83 or TI-84 series should be fine.

It is possible that some teachers may allow some other graphing calculators, but there is often keystroke-by-keystroke instruction in class so students with other calculators would be on their own as far as figuring out the keystrokes. Also this year's teacher may allow a different calculator but maybe not next year's teacher. There are a few TI-Nspire calculators that can emulate the TI-84, including the TI-Nspire with Touchpad (With available TI-84 Plus Keypad for compatibility) and the TI-Nspire with Clickpad (with TI-84 Plus Keypad for compatibility), but both seem to have been discontinued and are not recommended by the department. More advanced calculators, especially those with computer algebra systems (CAS), would probably be disallowed by most teachers. See TI's page for more information.

All the recommended calculators are also legal on the PSAT, SAT and SAT Math Level 1 and Level 2 subject, and the ACT Math tests. Many of the more advanced calculators with CAS, which are not recommended by LHS, are allowed on some standardized tests like the SAT, for which some of the CAS features might be useful, so you may want to consider getting one of those as well, but only if you will get enough practice with it. CAS stands for Computer Algebra System. These can solve some equations and even some calculus problems symbolically rather than with numerical approximations.

You can buy these locally (e.g. Staples) or online (often roughly half price if bought used). Even better, get them from siblings or graduating friends. If purchase is a hardship, you can probably get a loaner from the math department.

For the nerdy, there is a software program designed for Linux called TilEm that emulates calculators in this series. I have posted instructions for building TilEm on the Macintosh but those are way out of date.

There are software tools that can do much more than graphing calculators. For graphing there's GeoGebra. WolframAlpha can probably do any problem you throw at it, numerically, algebraically and graphically. I also have made a list of open source software tools.

The TI-83 was introduced in 1996, and the Z-80 microprocessor on which it is based was introduced twenty years before that. There is much more modern and, in some cases, more capable, software available for the phones most of us carry around all the time. Understandably, there is often discussion in town about how the LHS math department should update the calculator requirements. Rest assured that the math department has those conversations too; I remember them from over a decade ago when I was there. Here are some reasons why I still support this choice:

• These calculators, and others like them, are still allowed on most of the high-stakes tests students will take, and phone software and some of the more advanced CAS calculators often are not, so proficiency on them is important.
There is also often discussion about whether calculators are a good idea in school. After all, calculator use can lead to decline in mental math skills and laziness in problem solving. I still remember one eleventh grade student needing to calculate $$3 \times 10$$ in the context of solving an algebra problem, and I somehow managed to maintain my composure as he whipped out his calculator to do the calculation! These concerns are real, but I still think calculators are great tools when used in moderation. I tell kids that they should use calculators as we (should) use elevators in large buildings. To go up a few floors, take the stairs; it takes about the same time and we get free exercise. To go up a few tens of floors, unless we are in the mood to get some real exercise, take the elevator to save time and effort.