Saturday, September 13, 2014

No Calculators Allowed!

Ok, of course there's a time a place for calculators in math class, but in my classes I try to use them only when appropriate. It is a total shock to my Precalculus students when I tell them that they can't use a calculator on the first day of class. They're preconditioned to walk into a math classroom, grab a calculator from the classroom set, and sit down. The majority of the students say "I can't do this without a calculator" as we start to get into the math. It only takes about a day and half for them to realize I'm serious that you need to convert 325 degrees into radians without a calculator. It's not that I want them to be able to do 325/180 in a blink of an eye, cause I don't, but as I walked around the room this year and had quick conversations with groups of students it becomes clear to them why I'm taking away their "best friend" in my class. Believe it or not, and I know you'll believe me because you probably see the same things in your classes, a lot of students really have to think long and hard before they even realize that 5 is a factor of both of those numbers. That's when I explain to them the reason why I'm taking away the calculators is not so they have to do 180/5 on paper but because it's not automatic for them to know numbers that end in 5s or 0s are divisible by 5. Then we can also have a great conversation about how dividing 180 by 5 might be difficult, but 180/10 is not and my answer is half as large as 180/5. 

We have also had a lot of practice these first two weeks of school with fractions. Students don't even know where to begin with fractions, and by taking away the calculator they are forced to deal with them, forced to think about how they interact with numbers, and forced to finally learn fractions. One of the first homework assignments is a review of solving equations with one problem containing a fraction of a third and I'm always surprised at how many students change this to 0.33. I usually give an analogy the next day like if you have a dollar and have to split it with two of your friends, everyone gets 33 cents and a penny is left over. No biggie. And if you have $100 everyone gets $33 and only a dollar is left over. No biggie. But when you're rich a successful and you and your two business partners have to split $1 me up, I'll take your leftovers. It's a dumb analogy but the students like it and I get a lot of students to stop changing fractions to decimals like that. 

I do have a lot of motivation for getting the students to do more mental math since I teach a section of AP Calculus (more than half the AP test at the end of the year is no calculator) and most of my Precalc students will take AP Calculus the next year. It's only my second year at this school but historically our students have done the worst on the no calculator multiple choice part of the AP test. Maybe it's because the middle schools at one point stopped teaching long division, or other basic fundamentals that are going away that probably shouldn't. Anyhow, I'm trying to work on my students number sense and doing so by taking away their calculators. 

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