For this week's 7th grade task, I found a @ddmeyer task from his spreadsheet of tasks and added a few questions. I also took the answer video and put that at the beginning. The answer video did not have any numbers, but I thought it showed the students an excellent graphic of what this shrinking process would look like.
Here is what I presented to my students:
I think the biggest struggle for my students was the difference between percent growth/percent decrease, and the percentage remaining. To attempt to alleviate this problem, I emphasized that the growth or reduction should not include the original amount. We drew a few pictures to show this concept. I also related this to their own heights. We discussed what taking off an extra 100% would mean in this process as well. This wasn't prevalent with all my students, but it was the biggest problem.
I also had a few students confused with the wording of question six. If you can think of a better way to state that questions, please leave it in the comments. My goal was for them to see that while the sides decreased by 25%, the area actually decreased by 43% to 44% each time the dollar was shrunk on the copier.
As you will notice from the student work, most of my students use a ratio table method to work with all percent problems. I decided to present this as an option a few years ago because this method works for any proportion or percent situation, and the students understand what everything means. In the past I had student who would have to ask if they multiplied or divided in a percent scenario, but using this type of visual has alleviated that problem. Eventually, I have some students move on to other easier method that they figure out based on the ratio tables. In this task, I noticed a few students multiplied by .75 to find the 25% reduction. Other students spammed the divide 4 and multiply by 3 buttons on the calculator to simulate changing the whole to 25% and then 75% making the calculations quicker.
Here are the standards that I felt the task involved. I have also included the student work. One of the students commented that they saw a Despicable Me where they scanned their butt on the copy machine and could we try that next? I think we will stick with the dollar bills!
|My prep work I carry around on my iPad to help discussion with various groups and individuals...|
|I thought I would add this picture...a 7th grader trying to draw 5 millimeters with a meter stick...genius! This is why I love teaching middle school students...|
Previous Posts with Student Work
Tile Floor Task
Penny Cube Task