Demonstrate the concept of a limiting reactant using creative little gizmos. Using the average masses of the gizmo components, students calculate the number of gizmos that can be built from the materials provided. They then determine the limiting reactant in their set and the amount of each excess reactant left over. For final conclusions and presentation, predicted results are compared with the actual results. Developed by Nancy Fischer, the kit includes instructions and materials for 12 student groups. A balance that reads to 0.01g is required, but not included. Grades 8–11.