LegoMindstorms

Lego Mindstorms provide great hands on interaction with the real world.

http://www.legoeducation.us/eng/product/lego_mindstorms_education_nxt_base_set/2095 

The NXT kits provide excellent fully integrated solutions that bring in the tricky mechanically side of things...

Legos' are already designed to snap together and there aren't the issues of motor couplers and metal cutting.

The NXT microcontroller is an ARM7 based 32bit micro-controller. The ARM7 does vector point math instead of true floating point math and has some challenges with decimal number accuracy.

Labview for Lego Mindstorms is great for graphically teaching the core concepts of software control of mechanical systems.

My first impression of the Mindstorm Kits was that the system was too "canned" to be useful. Experience has demonstrated that the sensors provide great experience with non-idealities and the kits are really great teaching tools