Learners work with plastic sheeting, masking tape, and string to design the perfect material for plastic chair webbing, and then construct their webbing. Since the best webbing would resist stretching, learners then use a tension testing device to determine how their webbing reacts. This is a good activity to help learners understand the importance of choosing appropriate materials for particular applications. Resource includes instructions for how to build the tension testing device from basic materials. Appropriate safety equipment and adult help are required.