When i was at Secondary School, i joined a club at the end of the day where we built the machines that were to be used in the ICT Suite.
We were given the basic motherboard to which we would eventually install the CPU, Heatsink, Fan, Memory, CMOS etc... The teacher would show us what we had to do for the certain part we were fitting that day & we would then go away and do it, for example, the CPU, we would be shown the correct way a CPU should fit into the socked on the motherboard & how to secure it, then how to apply the heatsink & install the cooling plate on top. We would then go away and do this to the machines.
When all the motherboard stuff was complete, we moved onto the power connections and Hard Drives, CD Drives etc...
Once everything was complete, we installed them into the ICT Suite. We didn't touch any of the OS or software stuff, that was done for us but the teacher.
Just that little bit we did was useful for when i got to college & moved into other things like reseating Memory, installing a Parallel Printer etc...