Solving for a Variable – Relevance

CCSS-M has opened up my Algebra curriculum for explorations, and explorations are most productive when they motivate students to learn the rest of the curriculum.  Today we took 10 minutes to explore 6 lines of code before developing procedures to isolate a variable.  This TI-83 code was what I had on the board:

Disp “D=RT”
Prompt R
Prompt T
Output (5,4,”OUTPUT:”)

We discussed what each line might mean.  The students also recognized a familiar formula D=RT.  Then we decided to actually try coding with our calculators.  These students are mostly disaffected toward math when I get them so I am careful to watch for signs of disinterest.  There was none of that, so I continued down that path.

Programming with TI-83 is tedious because of the need to retrieve commands from the Catalog, so after the fourth line, we tested that much code.  There was obvious excitement as the calculators produced results and some perseverance when the code needed tweaking to get results.

Next we talked about how we could modify the code to produce R instead of D.  They saw what needed to be changed, and I asked them if they could modify code like that for a living.  Yes!

From there we rearranged current = voltage/(internal resistance), solving for R (below).  No one was even close to nodding off…a major victory for presenting this topic to this type of class.






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