# WeeklyMath Poll – Hybrid Car

Do your students still struggle with word problems? Do they ever ask you “when are we going to use this in the ‘real world’? If so, we’ve got the poll for you! This poll helps guide students through building linear equations that model the cost of two different cars over time, one hybrid-electric, one regular. This post highlights how polls can help you scaffold a problem and also how to use the scratchpad in combination with the prompt in rich math tasks.

The first task presents a word problem with two data points, one where the tank has a full 10 gallons and one where it has 8 gallons a month later.

The first task asks us to compute which car has a lower purchase price. In the scratchpad, I have pasted a picture of a table of values relating to lifetime cost and miles driven. Students can draw on this table or use any of the scratchpad features to compute the cost at 0 miles driven.

Since this problem asks students to figure out which car has a higher purchase price, students need to use the data to find how much the lifetime cost increases for every 50,000 miles and then work backwards to find the price at 0 miles. After students respond, I recommend displaying the results and then having a quick discussion to go over strategies and make sure they all were using a valid method. Students could get the right answer by just looking at the data for 50,000 miles instead computing it for 0 miles. I recommend making sure that students see how to compute that the purchase price of the Hybrid was 28,400 and the purchase price of the Sedan was 24,500. This will be helpful for the next problem where students were asked to model each car with a linear equation.

The scratchpad provides helpful support here in the form of a guided worksheet. Students can fill in the blank like they would in a workbook but now the answers are recorded digitally for you to analyze and organize. If you have students that want to solve it a different way or if they need more space, they can always move or delete the images. If you want use guided worksheets while making your own task, all you need to do is take a picture or scan of a worksheet and upload it in the scratchpad for your task.

If you are worried that your students might not be filling out the worksheet and just peeking at their neighbor’s screen or using other unsanctioned resources, you can always sort responses by work shown. In the example below, four students did not show any work and two of them still got it right, suggesting it might be worth following up with them after class.

For the students who got the task right and showed work, if any of them did a particularly nice job showing their work, you can pull up their response as an exemplar to show the class. You can even save it in the bookmarks (upper left) to show other classes in the future when you run this poll. Notice how this anonymous student used the text editor, the calculator feature and the drawing tool to show their work.