to square :side
  repeat 4 [forward :side right 90]
end
to csquare :side
  pu
  back :side / 2
  left 90
  forward :side / 2
  right 90
  pd
  square :side
  pu
  left 90
  back :side / 2
  right 90
  forward :side / 2
  pd
end
Your answer may look quite different - as long as it works!

Note how the first six lines move the turtle to the correct starting position with the pen up.

And then notice how the last six lines "undo" the first six so the turtle gets back home ok.