Scale Factor Candy Wrappers

My advanced 7th grade math class was at the end of their book, Stretching and Shrinking (CMP) and instead of having my students complete the normal book test I decided to have them complete a performance assessment. Performance assessments are something that my district is wanting teachers to incorporate in each unit if possible. The book Stretching and Shrinking has a unit project that involves having students enlarge or shrink a candy wrapper. So, I did a little research and looked on Pinterest to see what ideas teachers had posted there. The same idea of enlarging a candy wrapper was posted there.

I needed to wrap my head around this a little more so I talked things out with our art teacher, Mrs. Hart to get her take on this idea. The unit project and the Pinterest idea I found all said to have students draw a centimeter grid over their original wrappers and have them go from there. I didn’t want to use a centimeter grid so I wondered if I could tape the original wrappers on 1/4 inch grid paper and draw the lines through the copied papers. The art teacher, Mrs. Hart thought that sounded like a good idea. Below is what I started with. I decided to make 6 copies of each wrapper. 


From there I went ahead and wrote up some directions for this performance assessment/unit project for students. This is what I came up with. I then needed to decide on how many days I wanted to give students for this project. This class is longer than my other classes in that I get an extra 20 minutes or so with them. So they have about 65 minutes each day with students. At first I told students they would have Friday through Thursday to get their assessment/project done but ended up extending it one day. Two students needed the weekend to finish their work at home. So over all they had about 6-7 days to complete the assessment/project. 

I didn’t let students just chose which wrapper they got. I only made 6 copies of each wrapper and randomly drew students names to pick which wrapper they wanted. No one picked Air Heads and Mike Duds was the first one to go first. 

At first students were really excited about this assessment but as time went on they said, “Mrs. Martin you said this would be fun” they started to lose some of their enthusiasm but didn’t get upset about it. 

As students were working I did give them help if they asked and guided them back to their math binders to answer some of their questions. I was very happy with the conversations I heard between students while they were working and before they asked me for help they all asked their peers for help. 

While students were working I was walking around observing and taking notes. I noticed that only a few actually sat down and wrote out order pairs from the original wrapper. Most students just eyeballed where things went on their images. I heard students say, “This looks terrible”, “Can I change my scale factor”, “I’m a perfectionist so I can’t move on”. I saw students using a grid within a grid and some asked to use angle rulers. 

If I were to do this again I would expect students to find ordered pairs on their originals and show those to me before getting their grid paper to start drawing. I would also expect to see the new ordered pairs for the image. I would also restrict how large they could make their new image.

After students were finished this performance assessment I had them fill out a google form to give me some feedback on this performance assessment. All of them said that I need to do this again with students. Most of the students suggested that I restrict how large a student could enlarge their image. They also suggested that I allow students to bring in their own candy wrappers. 

Overall I am happy with how this performance assessment went. It did take longer to grade these than a normal test that I make. I also don’t like how much time it took out of class to get this performance assessment done so I need to look into that. 

This is what the final products look like. 


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About martinsarah

7th grade math teacher in Iowa

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