## Monday, February 15, 2021

### Charging Batteries - An exploration of Percents, Fractions, and Decimals

Today in class I used the Battery - Percents, Decimals & Fractions Desmos activity by Andrew Stadel.  Last week we had done a prompt to find 20% off and my students understood the context of percent off but did not clearly understand that it meant the amount they paid also had a percent attached to it.  For example, if you have 20% off, you pay 80%.  I wanted an activity that helped them better understand the complements that add up to 100%.  The Desmos activity uses the context of a charging battery and it was perfect.  I started with having students estimate the charge on my Chromebook.  They were able to easily tell me the charge on my battery, the percent used, and clearly understood that the two needed to add up to 100%.

From there we launched into the Desmos task.  It is great.  You really need to check it out.  Here is a quick snapshot to entice you.

The task itself is designed to help students make connections between fraction, decimal, and percent values.  We have been doing lots of work with Clothesline Math to help students understand the relationships between numbers and keep track of the different units in a problem.  We were able to use our clotheslines to help us see the connections as we discussed the batteries that were in the task.

I liked this activity and context so much I decided I needed a few ways to extend it to future warm ups in my classroom.  One thing that I wish I had had for my clothesline were the actual pictures of the batteries.  It could be much like Fraction Talks on a clothesline.  So I used the sliders in the Desmos activity to create this printable with batteries, fractions, decimals, and percents.

If you scroll down there is a section that has just the batteries.  With just the batteries I can have students place them on the clothesline, thinking about placement and spacing, and then they could come up with the fraction, decimal, percent values on their own.

I also really liked the slides that had students sketch using certain parameters.

It reminded of the Menu Math activities that Nat Banting shares on his website.  So I decided to make a Menu Math task using the context of the batteries.

This was my first time creating a menu math task and I loved trying to find the right combinations so that it could not be easily done in just 1 or 2 batteries.  My daughter and I tested it out and on our first attempt we were each able to do it with 4 batteries.  Plus I loved the discussions we had about some of the wording "at least", "up to", "no more than".  It was partially a lesson on inequalities as well.  You will notice I also tried to incorporate the amount drained/used in order to continue that discussion about the complements that should add up to 100%.

If you try these activities or have any ideas of other ways to extend this context I would love to hear about it in the comments below.