Classroom Stories: Teaching the Seasons in Inadequate Classroom Space
Classroom Stories: Energy and Kepler’s Laws: A Surprise for Me about Where the Difficulty Lies

Classroom Stories: Classroom Calculators

By Stacy Palen

Here’s the thing: all students have a calculator in their phone. And for a long time, I've thought, “They should use the calculator in their phone so they know how to use the calculator in their phone!” But here’s the other thing: a lot of those calculators are terrible. They don’t all do the order of operations the same way. They don’t all have the same “buttons” on them. They don’t all use the same notation. Therefore, any time I have students do any math at all in the classroom, I spend most of the time running around and helping them figure out how to put the “times ten to the” into their calculator. iPhone calculators are pretty good, but Samsung calculators don’t have the same functionality. Students must painstakingly type “(3 X 10 ^ 8)” rather than “3EE8.” That may not seem so bad, but if they forget the parentheses, the calculator doesn’t see their input as one number. So, if the problem includes division, the student is stymied. In addition, students' having their phone in their hand is distracting to the point of incompetence.

This semester, I had the idea to invest in a classroom set of calculators. I found a fairly simple solar-powered calculator that I could buy for less than $7, and I begged the chair of my department to use some of our lab fees to buy 60 of them.

When we have an activity involving a math problem, I invite students to borrow one, and I use the document camera to show them exactly how to punch things into the calculator. For Kepler’s Third Law, I show them how to square a number and how to take a cube root. For multiplying powers of 10, I show them how to put in “3 X 108” so the calculator interprets it as a single number (3EE8 or 3EXP8).

So far, this has been revolutionary. I spend far less time helping students with their calculators and far more time helping them think about their answers. Students can now help each other with the calculators, too, and they don’t need to wait for me to come around to them. Generally, this seems to be helping them be more patient.

Even for the many students who have their own favorite calculator, they sometimes don’t know how to use it for our specific purpose—it’s set up for stats, for example. While they have the option to borrow a calculator or use their own, I still spend some time helping these students find the “EE” or “EXP” key for scientific notation, but if they otherwise know how to use the calculator, they seem to remember this new function more easily. Looking back, I estimate that I could have bought only half as many calculators for the 70 students in the room, and even fewer if they work in pairs.

As I go along, I’m compiling a list of calculator instructions that I can print and tape to the cover. I may make a large poster of this information, instead, which might work better once we are back in our usual teaching space.

I have been pleasantly surprised by how much easier it is to manage the classroom when all my students have the same tool. In retrospect, it seems obvious that this method would be easier, but it took me nearly 20 years to think of it…

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