This activity was not really planned, I had the new coloured pegs in the boat dish ready to take outside and my son started playing with them.
So I told him to peg it onto the boat.
He soon realised that you need to put pegs on both sides to balance the boat.
He was very focused and stopped when he could fit anymore on.
He turned it over and said spider, Dylan removed extra pegs so it had eight legs like a spider.
This was good practise of fine motor skills, numeracy counting and colours.
To extend further for a pre-schooler you could:-
give them a sequence to follow
ask them to identify a patter in the colours.
ask them to predict if it will balance or tip.