Have an old computer or a variety of broken electronic devices that can be taken apart to show the Cubs the various components.  See how many they can remember and  pass the items around if possible.

*   Motherboard

*   Central Processing Unit

*    Fan

*    Power supply

*    Memory

*    Hard Drive

*    Cables

*    Resistor

*    Capacitor

*    Solder

*   Controller Card

*   Etc.