Introducing Exponential Growth

Just thought I'd share how I introduced exponential growth to my Algebra 2 students.

For a warmup assignment I asked my students if they would rather have a million dollars today or a magic penny that will double itself for 30 days. Students wrote down their answer and why, then we took a vote of who would choose each. (most chose a million muahahaha)

We then began the story One grain of Rice by Demi.



The story is about a girl that convinced an unfair Raja into giving her all the rice he had taken from a town by having the amount start with one and double for 30 days.

After we've read about a couple of days we start to guess how much she will end up with and see who's answer is the highest to put on the board.

We finish reading the story and students tend to be pretty shocked that the one grain of rice turned into millions and then billions total.

After the story we filled in this worksheet from Illuminations.

Most students needed a little help coming up with the equations on their own. We looked at and discussed the pattern between the total after so many days and the next day after that together as a class.

Over the next couple of days we graphed, wrote and solved some exponential problems and I found myself referring back to the story quite often. 

I think my students enjoyed the break from math to enjoy a story and it was kinda fun for me to have story time as well. I believe this is my third year now introducing exponential equations this way.

Distance & Midpoint Formula

Just wanted to share an easy way to get your students to practice the distance & midpoint formulas.

Print off a class set of what I think of as skeletons for the two formulas.

Put each paper into a clear sheet protector.

Hand each student the sheet protector, a dry erase marker and something to erase with.

After students have been given the formulas you can give them two points to practice by filling in each step and working down to the answer.

The scaffolding helps students work out each step. The hardest part for them will be adding/subtracting positive & negative integers.

Then for homework assign practice problems without the scaffolding.

My students had a lot of fun working on problems and even asked for a couple more to work on. I've used these a couple of years in a row now so I just keep the papers in the protectors but I have some other papers I change them out to. (synthetic division, graphing lines, box method and factoring by grouping) The sheet protectors are way cheaper than a class set of white boards and its nice to put that paper inside with some steps for them.

If I knew how to upload the files I would :( Sorry.