You’ve heard the old saying, “If you don’t use it, you lose it.” Scouts need to practice their knots on a regular basis.
Create plenty of opportunities for Scouts. That’s right, create the opportunities. If you currently use pre-made tent tie downs, have the Scouts use a taut line hitch instead. When clothing gets wet, have a Scout tie a bowline to a tree and make a clothes line to dry their gear. Challenge the Scouts, and yourself, to tie a one handed bowline.