Define a real design problem that a magnet can solve, such as keeping a lid or door closed, then build and test a magnetic latch.
Engineers use science ideas to solve real, everyday problems. Here is one: how do you keep a box lid, cabinet door, or bag flap closed without a lock or tape? A magnetic latch solves this using a magnet's pull: one magnet (or a magnet paired with something magnetic, like a steel washer) is placed so the two parts snap together and hold the lid or door shut.
Good engineering design starts by clearly stating the problem, then builds a first attempt, tests it, and improves it if it does not work well enough the first time.
Mastery looks like: They build a working magnetic latch and can describe at least one design change made after testing it.
Common stumbles: Expecting the very first attempt to work perfectly without any testing or adjustment.