CLASTIC SNACK ACTIVITY: TEACHING CONCEPTS OF ENERGY, DISTANCE, AND TIME IN SORTING

A class activity using a small bag of unsorted, mixed snack food of different sizes demonstrates the sedimentary concept of clastic sorting, as a function of energy, distance (proximal vs distal) and time. The students are “water”, and the snack pieces are “clastic grains”. Time is a proxy for energy and transport distance. The task is to take the unsorted snack food and sort it into different piles.

Two options are presented here: 1) in-person, and 2) virtual or online. About 6-8 types of small, non-greasy snack foods like pretzel bites, cereal, and candy work well for this exercise. Typically, students initially sort by size, and then by color or texture. In option 1, the instructor provides mixed snacks, individually wrapped in a napkin (so students can’t see what’s there ahead of time) and in a plastic bag to keep it contained. Follow all proper health and food-handling rules. Students initially open the food bag, starting simultaneously at “go”. Then at short, successive, prescribed time intervals (e.g., 20 seconds), the instructor calls time, at which point students look up, stop sorting, and report how many piles they each have so far before returning to sorting for the next time interval. A graphical plot of reported piles vs. time shows a nice trend of more piles and better sorting with more time. This exercise can also be done by visually impaired or blindfolded students as well, as tactile sorting may be equally effective. For option 2, a household member could prepare the small pile of mixed snacks and be the timer, or students can watch a video of the activity prepared by the instructor.

Students discuss their criteria for sorting and see the analogy of how big grains are the first to come out (proximal) and smaller sizes are sorted later (distal). Their favorite part of the activity is eating the snacks afterwards, while cogitating clastic sorting.