Create a circuit that has no metal wires and uses at least three different conductors.
Build an open circuit that completes when the water level drops below a certain level and/or goes above a certain level.
Build a dinosaur at least 6" tall that can balance on two legs using counterbalances.
Build a crane that uses simple machines and mechanical advantage to move heavy objects.
Build a stomp rocket that can carry a ping pong ball and hit a target.
Engineer a sensor that can detect how much fuel is in your tank
Build a device that opens up when thrown in the air
Plan and build a network to send communication signals in multiple directions to multiple people.
Build a wing that can generate lift from a fan while carrying weight.