Axle - A LEGO Technic piece used to allow wheels and gears to spin freely, and to hold models together.
Beam - A LEGO Technic piece used to stabilize models and add structure. Has holes through the side.
Brick - A basic LEGO piece with studs on the top. They differ in size and color
Connector Peg - A LEGO Technic piece that can be used to connect beams and other elements with holes in them together.
Gear - A LEGO Technic piece used to transfer energy from motors etc to wheels.
Motor - A LEGO element that can be used to drive pieces like wheels and gears. Appear in Technic and Mindstorms LEGO sets
Plate - A LEGO piece that is 1/3 of the height of normal LEGO bricks
Sensor - A LEGO Mindstorms element used to detect sound, objects, light, touch etc.