This activity requires a great deal of strategic thought from the students, as well as a thorough understanding of chemistry concepts. In order to be successful, students had to determine a way to measure the exact capacity of their bag, calculate the amount of chemicals needed to produce enough gas to fill the bag, and devise a strategy for keeping the chemicals separated until the bag is sealed in order to prevent gas loss.
One way that I differentiated the activity was by having hint cards that could be used for a small penalty. Students could request a hint card at any point in the process. The cards offered suggestions for how to measure the bag, how to carry out the calculations, and how to separate the chemicals while sealing the bag. The competetive nature of the activity caused students to save the hint cards as absolute last resorts.
This proved to be a great culminating activity for my students. They had to have an in depth understanding of gas laws and stoichiometry in order to be successful. I'd love to hear about your favorite lab! Please share in the comment section.