Large climbing rope.
- Tie three or more simple overhand knots in the rope.
- Ask all the group members to hold on to the rope.
- Ask the group members to untie the knots, without letting go of the rope.
- Sliding your hand up and down the rope is permissible.
- We have also asked groups to tie knots in the rope using the same format. For some reason, tieing is more difficult than untieing... Any explanations for that? :)