Wednesday, January 6, 2016

A trick on the TI Calculator

I know, I am a blogging machine. I'm sure it will slow down verrrrry soon.

Just wanted to make an observation in case in can help anyone else.  Or maybe I'm the only crazy fool who didn't know this?

In Math 3 (think Algebra 2ish) today we started finding zeros of polynomials that wouldn't factor. You know, the big messy ones. For now we're keeping it real but will move on to those that have imaginary solutions soon.

So I was showing the kids how to graph the equations and use the calculator to find zeros.

I totally showed them Desmos first because it's so nice and easy... all you have to do is click the x-intercept and it tells you the value!  Magic.  But I'm not going to let them use their computers on a test, so I wanted to make sure they know how to use the calculator, too.

Anyway, we graphed the function, found the zero option in the calc menu (these kids are so unfamiliar with the graphing calculator that it's scary) and then went about the business of finding the zeros.

I always struggle showing the kids how to move the little "spider" so it's on the left side of the zero here and on the right side of the zero here.  But did you know that you can type in values for your left and right bounds?!  Not only does it avoid the using your arrows to move around the screen, but it encourages the kids to actually look at the values in the graph to know their zero is between two certain numbers.

Considering that from here we went to synthetic division to divide out the "nice" zeros and then quadratic formula to solve the resulting quadratic, I didn't want the kids freaking out about having to use the calculator to find zeros.  This definitely helped.

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