Pringles design challenge

The Pringles design challenge is a laboratory-based formative assessment tool for learning about how students think about controlling chemical reactions. It has been tested in high school chemistry classrooms in the US, and in university chemistry classes in the US, Mexico, and Costa Rica. The tool is available in English and Spanish.

This formative assessment requires a laboratory setting (with proper safety precautions) and about 3 hours of time. This can be done as a single 3-hour laboratory session, or as shorter laboratory sessions over several days.

To use this formative assessment, provide students with the handout explaining the challenge (see versions below), and then demonstrate the safety precautions before any students begin. Safety precautions that should be demonstrated, and then rigorously enforced, include: (1) insist that long hair be tied back and that loose clothing be secured, e.g., wearing a lab coat, (2) everyone must wear safety goggles, (3) the Pringles can must be set within an iron ring on a ringstand, to prevent the can from falling over (you will need larger sized iron rings for this), (4) the cap must be on the Pringles can before igniting the lighter, (5) always turn off the gas jet completely when not using it to fill a syringe, (6) when igniting the lighter at the hole in the Pringles can, stand to the side in case a flame shoots out of the hole, and (7) if the Pringles can begins to char around the hole, it means the coating is wearing off and there is a danger that the can could catch fire, so replace the Pringles can with a new one and throw away the old one. For further information, please see the  Safety Protocol for Teachers.

Students should navigate the process in design cycles, in which they first brainstorm and plan what to do, then try it, and then consider the results before continuing with a next cycle. Teaching tips:

• Let students flail and realize for themselves what chemistry is relevant to this. Success is sweeter when it doesn’t work the first several times and students have to figure out themselves what to do to make it work and why that is.
• Competition can be fun. One way we have found works to conclude is to have a competition at the end where students decide how to determine who wins. Ideas that students have come up with in our tests of this tool have included loudest bang, highest flying cap, and most exciting presentation.

Handout versions:

•  Exploding Pringles Can Design Challenge for one long class period [English]
•  Shorter Laboratory Sessions over Several Days [English]
•  desafiopringles.pdf [español] 

Safety Note: In the US, the gas in laboratory gas jets is methane. In other countries it can be a mixture of propane and butane, which burns at a higher temperature. Find out first which gas is used so that you can have a sense of what to expect, and what amount of gas your students will eventually figure out that they need to make the explosion work.