Engineering project activity for STEM curriculum in grades 4-12. Students will design, build and test a structure made of index cards. You will need index cards, masking tape and a scale to weigh the structures and to get a weight on the textbook. The activity sheets include: Introduction, Equipment List, Procedure, Design, Predictions,Test Results, and Conclusions. You may use weights such as textbooks to stack on top of the completed structures to see how much they will hold before collapsing. The test results section requires the students to take measurements and use formulas to calculate the total weight held and the efficiency rating. The conclusion section includes 5 reflective writing prompts. The students can complete this activity individually or with a partner for a collaborative learning opportunity.