Designing Your Lesson -- Machines That Help

In designing your Machines That Help (MTH) lesson plan, you probably won't get very far without doing the activity yourself. Just as students need to become familiar with the materials they are designing with or the product they are redesigning, you'll need hands-on experience with the MTH task before designing your lessons.

As is true with many design challenges, you can have students generate design ideas at various stages of the unit: right after they read about the challenge in the design brief, after a series of teacher-taught lessons on simple machines, or after completing their own hands-on investigations with simple machines. The Nuffield approach to this issue might have students start with short design-and-build tasks (resource tasks) involving simple machine demos, which would then help students in proposing their final projects (capability task) of their own choosing that involve some collection of simple machines. The Design It! approach might involve more hands-on building of machines with supplied materials but no plans, followed by lessons on simple machines and plans for certain machine types.

One of the key choice for you as teacher in redesigning MTH for your own classes is to decide when and how to end the challenge. Do you want to have students build a machine that at minimum provides a Mechanical Advantage of a bit more 3 (depending on the precise Load and the strength of the thread you choose to provide to students)? Or do you want to have students produce a device that can lift the heaviest object when mobilized by the force that the strand of cotton thread can transmit without breaking? NOTE: The latter design challenge would probably need an additional constraint to keep students from proposing solutions that are unwieldy. For instance, the machines that students design might be required to use structural elements that are no larger than a given size, or the entire device might be required to fit within a certain volume (inside a cardboard box that you supply). The latter approach is used in the FIRST competitions, since the robots that students devise for FIRST must be able to fit a given shipping container, and weigh less than the amount pre-set by the shipping company.