I had an interesting experience today in our fourth grade open ended engineering challenge. The students have to build and market a burglar alarm using the Lego WeDo Robotics Kit and Resource Kit (extra parts). One team had the tilt sensor attached to a burglar on the burglar’s airplane. So what is wrong with this? You might think that it is just too unusual. But, the way I think about it and the way I explained it to the student, was that it did not meet the requirements of the burglar alarm. By the way, this is a very common problem in engineering in my experience!
So I explained it like this. The burglar alarm has to be very general; it must stop any burglar from entering the house. Also, how could you get the sensor on the burglar’s plane in advance? The student was actually arguing that you could but I think he just did not want to give up on his cool plane and cool idea.