You add one mother who builds the first model.
You add oh.. "what's that mom?" and interest follows.
Add frustration. "MOM! it doesn't float!!!"
You add encouragement... so what do you think will make it float?
One receives "I don't know" as the answer.... to be responded to with "so, think on".
The next day a lad has thought on it and so tears off the top of the model (which he has deemed as useless and turn it upside down). Tries that.. still doesn't float.
Then he breaks into our "build stuff with in bins" and pulls out a jar.. this might do it mom!
He comes across some foam.. think think.. will it float. Test out the foam first. YES!!! it floats!
Cut it to size and voila!
Now.. will the paddles work?
A wee bit but not much... hmm...what to do.
Together we did some problem solving. We saw pictures of what real paddle boats look like and how they move water...how can we do this using ONLY K'nex (I suggested using tape or paper but NO we were to use only K'nex).
The lad's solution
Our various efforts changed the forward motion of the boat from 1 inch active movement to about eight inches...with floating lasting a good half length of the bathtub. This was deemed a rousing success and promptly lead into a battle twix the birds and the pigs... The pigs ended up having better guns so they won.