This is a set of 20 task cards that I created to use with my students as they learn ratio and proportion.
Twelve of the cards have a shape and students are given the scale. They must measure the shape with a ruler (cm or inch) and then calculate the actual size. The final eight cards give the shape and tell the students the actual size of the object. They must work backwards to find the scale (1 cm = n). The measurements fall either on the whole inch/cm or the half inch/cm, and the cards range in difficulty level from basic to challenging.
I typically have the kids work in pairs to solve these problems, but they could be used for a math center if students had experience with scaling. (I also print the cards directly to a printer because I have issues with the copier at my school slightly shrinking images and it throws off the measurements.) I found that my students were particularly challenged when a measurement included a half an inch or centimeter, and it was great practice for how to interpret the scale. They also needed more discussion when the scale itself was based on 0.5 inches, rather than a whole inch.
I used these to help students with proportional thinking (Common CORE 6.RP.3), but they also address 7.G.1.
This is a 7-page PDF file that included 5 pages of task cards (4 per page), a 1-page recording sheet, and a 1-page answer key.