The Great Spaghetti-Marshmallow Challenge.
The task: construct the tallest possible structure using 20 pieces of dry spaghetti, a meter of tape, a meter of string, and a single large marshmallow, which was to be placed at the top of the structure.
Consistent with research, no group in either homeroom was able to complete the task. Sad. Why? As with adults, our students initially focused on building tall, and only at the last minute considered placing the marshmallow. Their tall towers then collapsed, the designers having underestimated the weight of the marshmallow.
Among the best at this task are Kindergarteners, who tend to BEGIN with the marshmallows, and prototype along the way. The lesson: prototyping matters!
For an overview of this activity, see the TED Conference presentation by Tom Wujec.