Circuit investigations

What is a circuit?
a) i) Using the equipment you have, test each of the following circuits. Put a tick over it if it works, or a cross if it doesn't.
  1)   2)   3)
  4)   5)   6)
  ii)
Why do some of the circuits work, while others do not?
 
 
 
b) Now make up these two circuits.

A B
  i)
What did you find out?
 
 
  ii)
Explain why this happened.
 
 
 
 
 
c) Make up these two circuits and explain your results.

A B