A flywheel is a mechanical device that stores rotational energy. Basically, it stores energy by spinning. Your Disc Launcher uses the rotational energy (spin) of the flywheel to launch its discs. When a disc touches the flywheel, the flywheel gives some of its stored energy to the disc.

A ratchet is a device that allows rotation in only one direction. Basically, it only turns one way. It uses special teeth to lock a wheel in place. For the Coin Spinner, when you pull the ratchet back, the teeth lock to store the energy of the rubber band until you release it with the trigger. Then, it transfers stored energy to the coin.

Momentum transfer is motion passing between objects. Basically, one thing bumps into something else. When the Trip Wire is triggered, the kicker lever swings into the foam ball. The energy transfers from the kicker to the ball, just like kicking a soccer ball. Energy is never lost!

A linkage uses pivoting bars to guide a machine’s movement. Basically, linkages help things move. The Drawing Machine uses linkages to guide a pen in complex but predictable patterns. The arms are connected to wheels that spin at different speeds. The arms also pivot in difference places, changing where the pen goes.

Projectile motion is the curved path of a launched object. Basically, it’s the science of tossing stuff. Domino Catapults can launch balls to the same spot over & over due to projectile motion. The motion of a projectile is affected by the angle (trajectory), the force (velocity), and gravity. Keep those the same each time you launch to predict where the ball will land.

Light reflection is light hitting an object and then bouncing off of it. Basically, it’s light changing directions. The squirrel animation is made by etching tiny scratches into clear acrylic. The light wants to pass through the acrylic, but when it hits the scratches, it gets reflected out the front. That’s why the squirrels appear to be glowing!

Mirrors are smooth surfaces that reflect a clear image. Basically, it’s light changing directions. Your Mirror Bank uses the reflective surface of a mirror to create an illusion of an empty box. The box is only half empty, but because the mirror reflects the empty half perfectly, your eye is tricked into seeing one entirely empty box.

A worm drive is a gear that changes the axis of rotation 90°. Basically, it’s a gear that turns a corner. Worm drives are often used to change the orientation of gear. Notice that the Boomerang Car uses a worm drive to flip vertical rotation from the motor into horizontal rotation of the red & blue switch. As a result, the Boomerang Car’s motor, wheels, and switch all move as one.

A belt is a loop of material used to carry objects or transfer energy. Basically, belts move stuff along. The belt on your Duck Game carries the ducks in an endless loop. The rollers drive the belt forward, bringing the ducks along for the ride...

A spring stores mechanical energy through elastic deformation. Basically, springs store energy by stretching. The spring in your Airplane Launcher stores energy when you pull your string back and releases energy when you let it go. Your spring returns to its original shape after being stretched due to elastic deformation.

Compressed air holds a greater pressure than the atmosphere. Basically, it’s tightly-packed air. The Rocket Revolver is powered by compressed air. When you stomp the pump, you're pressurizing the air inside. That air wants to escape back into the lower-pressure atmosphere. The only way for the air to escape back into the atmosphere is by shooting the rocket out of the way.