This is a set of 16 task cards that present two similar rectangles with some sides labeled. Students must use proportional reasoning to find the missing length. All sides are labeled in whole number units and can be solved with mental math. Shapes on the first cards are presented in similar orientation and on later cards are rotated. Students must find both missing sides on the enlarged shape and missing sides on the smaller shape using their knowledge of corresponding sides.
This is an 8-page pdf file that includes 4 pages of task cards (4 per page), a half-sheet recording sheet for students and answer key with blanks, and then an alternate recording sheet and answer key with a proportion to be completed and solved..
I designed these cards to use with my above level fifth grade math students to help address an increasing number of standards in Common Core that focus on proportional reasoning. Students needed to be able to identify corresponding sides, but could solve for the missing length without formal knowledge of solving proportions with cross-multiplying. They found the cards challenging when the orientation of the shapes is rotated so that corresponding sides are not as obvious.