Make quick knot boards using card, twigs and paracord.
A4 card (various colours), twigs, paracord or string (preferably in a selection of colours), hot glue gun.
Teach the Cubs/Scouts several different knots. Once they can tie a knot, glue the completed knot to the knot board using a hot glue gun (carefully!). To help remember the names of the knots write it underneath, or provide pre-printed lables for a smarter look.