School work - a boat

After school on Friday, BallFiend was telling us about his day. He said he had made a boat using "those blocks that you nail into a piece of foam" and was trying (with some difficulty) to describe what he had done. So I suggested he draw us a picture. 

Everything in this picture is BallFiend's drawing, except for the two trapezoid shapes
which he asked me to draw. (The scribbled-out shape on the left is his first attempt at a trapezoid that he was not happy with!)

After drawing the boat, he added the "half-a-circle shape" (ie. semi-circle) and the "circle with a face on it" at top of page when he was explaining that there were other blocks available but he didn't use them.

I thought his teacher Nerida might be interested to see this drawing, so I emailed it to her and this morning she sent me back a photo of his original boat: 

Nerida said that they looked at it as a class, turned the photo of it into a diagram and wrote about it.
I'm still not quite sure where this is all leading... maybe he's going to be a boat builder or something. (And given the amount of rain we have had today, we might be needing an ark!)

And I'm yet to find out from BallFiend what the yellow circle represents, but I do like the way that, amongst all the angular blocks, he has ensured that his favourite round shape is included.
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Update, 28 February: I found out that the yellow circle is the propeller. Duh! 
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