The Power of the fx-991EX – It’s Not JUST Solar

I read the Casio Twitter feed and FB feed every day, just to answer questions and see what followers might be saying. Recently there have been some kudos shared about the fx-991EX solar powered scientific calculator that got me curious. In particular. that the fx-991EX does engineering problems so well and they would be lost without it (someone said he uses it in all his higher-ed courses). This was intriguing to me since I assumed engineers, with their complex calculations, would more likely use graphing calculators like the Prizm or ClassPad or even engineering software.  Naturally, I set out to explore some of the ‘engineering’ capabilities of the fx-991EX, since I hadn’t really spent too much time with this aspect of the calculator.

As I refreshed my memory of the menu and capabilities of the fx-991Ex, it kind of boggled my mind how
much this solar-powered scientific calculator can do, and with it’s QR code capabilities, it can even show graphs and printable spreadsheets and tables. (See my previous posts about Graphing & QR code capabilities). After looking a little more closely at all the menu icons and what each does, I understood why this one calculator would in fact be sufficient for engineers, or really anyone. I spent some time playing around with different features that I had not previously explored, and have shared a couple of my explorations in the video below.

For those of you who have not experienced or explored this powerful little calculator, I suggest you do. If you are at NCTM San Antonio this April, stop by the booth and get some hands-on experience, or just explore some of the videos, or download the free 90-day emulator trial and give it a go.  You can access our Quick-Start Guide to get you on your way.

Solving Equations with A Scientific Calculator

Solving  equations is a skill that students are expected to be able to do in pre-algebra and beyond. If we look at the Common Core State Standards, these skills actually come into play starting as early as 6th grade, with students expected to solve one-step equations and progressing to systems of equations by 8th grade. An important aspect of solving equations is connecting a real-world context to these and understanding what the ‘solution (s)’ mean in terms of that context.

The use of calculators or technology to help students solve equations is a controversial one at best, and as a math teacher, I do believe that students need to know the processes to solving equations without the use of technology first. But – when we get down to real-world application and problem-solving, the technology becomes a tool that allows students to go beyond just “getting the solution” and to making meaning out of those solutions, and using their solutions to make decisions – which is the ultimate purpose of finding those solutions, right? In these cases, I firmly believe that the use of technology, (more often than not a calculator), is a necessary tool so that students deepen their understanding and are not bogged down in the process of the calculation. Part of the practices – “use appropriate tools strategically”. 

As an example, let’s consider a simple real-world context that involves solving a system of equations, something required by the time students reach 8th grade (see Common Core Standards). Let’s say a scientist is mixing a saline solution and has one solutions that is 10% saline and the other 25%. He needs to make a 85 ml bottle that is 15% saline. How much of each of the two solutions should he mix to create the 85 ml bottle of 15% saline? This requires our two equations, with x = the amount of 10% solution and y= the amount of 25% solution.

  • x + y = 90 ml
  • .1x + .25y = 12.75 (15% of the 85 mL saline)

Perhaps students are actually in science class doing a lab and creating this new solution. While it would be reasonable to do this by hand using substitution, if this is part of an experiment, then using a calculator to get the answer quickly and therefore get on with the experiment might be a more logical step, especially when time is of the essence in classes. I am going to demonstrate on the fx-991Ex how to solve this problem.  I am using a scientific calculator because in middle school, students are more than likely going to have access to these versus a graphing calculator. This video shows how you can quickly solve the simultaneous equations, and also, with the QR code capabilities, also see a graphical representation of the solution.

If a scientific calculator is all your students have access to, remember that they can do a lot more than you might think.  I will explore more features of the ClassWiz in later posts as we continue to explore mathematics and using technology to support learning.

Histograms with ClassWiz & QR Codes

Students should engage and be hands-on with mathematics as much as possible. One of the activities I loved was the Sum of Two Dice, whether in my middle school classes or in my Algebra classes. That’s the great thing about mathematics – you can take an activity/concept and make it more or less rigorous depending on the questions you ask.

I am sure many of you have done this activity – I am choosing it for this post because it’s a nice way to 2015-12-10_11-23-28demonstrate how the Casio ClassWiz (fx-991EX) scientific calculator allows you to create frequency tables and with the QR code, see an online visualization of the data.

First thing – have students roll two dice and collect some data – i.e., the number on each die and then the sum of the two together. If you don’t have die (or don’t want to hear all the noise!) you can utilize the random integer option on the calculator to simulate rolling die. I usually had my students in pairs to do this – one record, one ‘roll’. Then have them tabulate the frequency of each sum and create a new table with possible sums & frequency.

2015-12-10_12-32-42The next step is to have them make a histogram of their own frequency table and then compare to other students.  In my example, students only rolled 24 times each, so everyone’s graph will look different and not be what we expected (more 7’s). Great discussions can come from these observations.

Hopefully, discussions lead to the idea that each group o2015-12-10_12-17-22nly collected a small sample of rolls, and that if we had more samples,
perhaps the distribution of data would be more what we expected – i.e. more sums of 7 appearing. Here’s where having a class emulator is a great tool – you can display one frequency table and collect the class data.  So – same sums, but combine each groups frequency to get a total frequency for the whole class.

Once you collect the class data, you can then create a new histogram. With the 2015-12-10_12-18-07ClassWiz you can easily do so just by creating a QR code of the table data, and, with the emulator, go directly to the visualization. You can also do this with the SmartPhone App Edu+ if you have that option. The nice thing about the emulator is you can immediately pop the visualization up and begin discussions and comparisons of whole class histogram versus individual groups. Being able to immediately see the visualization with only a scientific calculator, is powerful, especially as you can quickly compare between previous “one-group” histogram and current “whole-class”.

There are so many ways to use this activity – I use to use it with TinkerPlots, graphing calculators, students hand-drawing the graphs. The ClassWiz and its ability to create QR codes and online visualizations is another way to help students make meaning out of the math they are doing, especially when they only have a scientific calculator to use, as most middle school students do. Hopefully this gives you some more options.  I have included a short video clip on how to actually create the frequency table, QR code, and online graph using the ClassWiz fx-991EX. Try it!