### Doing the Math

Good things may come in threes, but TI has a pair of winners for math and science classrooms. The TI-84 Plus C Silver Edition color calculator is for teachers and schools that prefer a traditional standalone device while the TI-Nspire and CAS iPad apps are for those who have built a curriculum around Apple’s tablet.

To start, the TI-84 Plus C Silver Edition picks up where the monochrome Plus Silver Edition leaves off. The 7.7-ounce case is lighter than the monochrome model, looks the same and is available in black, purple and blue. Like its earlier cousins, the Plus C comes with a slide-on cover.

It has an identical button layout and uses the same key sequences, so moving from to the other is a snap. In other words, the Plus C look like a clone of the Plus model that can work your library of math files, all of its accessories as well as the Vernier digital sensors, but there’s one important step forward: it has a bright and rich 2.8-inch color screen. The 140 dot-per-inch display can show 16-bit color in vivid 320 by 240 resolution.

It may not be impressive compared to a notebook or tablet display, but it is brilliant and able to show everything from simple arithmetic to complex integration and just about any graph you can think of. The numerals and graph lines appear so bright that they just about jump off of the screen, particularly when compared to the older monochrome displays.

Inside is the same 15MHz Zilog Z80 processor as the TI-84 Plus family as well as 3.5MB of Flash ROM. The calculator has 21KB of RAM available for work and apps, which should be more than enough for most work.

It’s all powered by an 800 milliamp-hour rechargeable battery pack rather than the Plus’s four disposable AAA batteries. It can be recharged with a micro-USB cable and should be able to run for several days of on and off use on a charge. The cable doubles as a way to communicate between calculators and it comes with a plug-in charger and cables.

The Plus C’s operating system is just as impressive with an integrated polynomial root finder as well as optional apps for solving inequalities. So much more than a calculator, the Plus C can solve and graph all kinds of equations. On the downside, its keypad has become so complicated that it can take students and teachers a long time to get the basics down and never truly master it. The multi-color markings help, but it can be rough going.

It’s an excellent way to show off equations with images that can easily be downloaded into the TI-84’s memory. To my thinking, there’s no better way to make the shape of an absolute value function more memorable than to overlay it on top of a V-shaped roof.

However good the TI-84 Plus C is, it is limited by the 2.8-inch screen and its $150 price tag, about $20 more than the monochrome version. If that’s too much, TI is giving some of them away. You need to be a US citizen and register on the company’s Facebook page before April 21.

The TI Nspire Apps for the iPad are not limited by the calculators constraints, but have their own pros and cons. There’re two programs available: one emulates the Nspire line of calculators and button sequence and the other uses TI’s CAS system. They cost $30 each, but there are no volume discounts for outfitting a district at a time at this time.

The software is downloadable from the iTunes App store and like the standalone calculator, the app can work with images and use existing .tns documents from a hardware calculator. Because the Nspire iPad app works with the entire screen, it provides an incredible view of math, from simple equations all the way to complex statistical distributions. You can use the iPad’s email client and WiFi to distribute tests or park homework and worksheet files online in a Dropbox account.

The software comes into its own when connected to a projector, but you’ll need Apple’s $50 adapter or use Apple TV to do this. There’s nothing like punching in sine, cosine and tangent curves to visually illustrate the relationship between them.

As cramped as the hardware calculator’s keypad is, the software equivalent is spacious, well laid out and takes advantage of the pad’s display space. In addition to a central numeric pad, to the right are the major operators and to the left are trig functions as well as a slew of powers, variables and calculus operations. It should only take a few lessons before everyone is familiar with its design and many will pick it up right away.

In addition to directly inputting an equation to be graphed, you can start with raw data in spreadsheet form, perfect for use in a science lab or to explore real world statistics. The app has six different graphing styles and you can choose from a palette of 15 colors for the axes, lines and backgrounds.

It’s easy to change equation variables to show everything from translations to the effect of changing the sign of a function. At any time you can zoom in and out to see visually key in on details.

The app includes several lessons, including an animated skateboarder rolling through a parabola that shows the relationship between potential and kinetic energy. Not only can you change the shape of the track, but the amount of friction and gravity can be adjusted. More are downloadable on TI’s Web site.

It does statistics as well and can work with normal, Student T test, Chi Square, binomial and Poisson distributions. There are ten standard testing functions built-in.

As good as the app is, it’s not perfect. It only works on second- and third generation iPads and there’s no Android software at this point, a major problem because Android systems are much less expensive than iPads. On several occasions using the Nspire app, the iPad Mini ran out of memory to do additional things. Plus, the system doesn’t work with Vernier’s digital sensors.

The biggest disappointment is that because it is part of a tablet, it can’t be used on any standardized tests at this point in time. That will likely change, but it means that anything that is taught with it needs to be relearned with a standalone calculator when it comes time to take the ACT, SAT and AP tests.

While there’s no shortage of free iPad graphing calculators, this one is so comprehensive that it is worth the money, particularly for schools that have distributed iPads to the entire student body.

**A**

Price: $150

*+ Impressive screen*

*+ Continues with TI-84 layout *

*+ Rechargeable battery and AC adapter*

*+ Impressive built-in apps*

*- Expensive*

*- Cramped keypad*

**A**

TI-Nspire Apps for iPad and TI-Nspire CAS App for iPad

Price: $30 each

http://education.ti.com/en/us/products/apps/ti-nspire-cas-app-for-ipad

*+ Works well with iPad*

*+ Can use entire iPad screen*

*+ Uses familiar layout *

*+ Graphing flexibility*

*+ Inexpensive*

*- Need a classroom of pads*

*- Doesn’t work with first generation iPad*

*- Not approved for tests*

- Doesn’t work with Vernier sensors