The students are given instructions to follow so they can keep track of which line segments have been measured and can do them in a logical order. This year with my 8th graders I decided to put them in pairs and give them different scales to work with. I had various sizes of grid paper available for the students to use. (In the past I have taped sheets of graph paper together to make larger pieces.) They drew the images with 1:.5, 1:2, 1:3, and 1:4 scales. Having them complete the project in pairs worked out great as they problem solved together. I would walk around and spot check some of their measurements as they worked because a mistake on even one measurement can throw off the rest of the drawing.
Once the students finish the scale drawing I allow them to design the jet however they would like. To grade the project, I choose several line segments to measure and grade for accuracy.