Walter Whiteley sent this link and powerpoint that you might be interested in

Hi all. Walter Whiteley has sent us an interesting link on using 3D printing with Grade 4 kids to design a boat that floats and bears weight, using geometry in the design. (I could certainly imagine doing this with physical materials apart from 3D printing as well...)

Walter also sent a brief 2-slide powerpoint about different kinds of geometric transformations (affine, projective, etc.) that preserve different kinds of invariants.

Many thanks for a wonderful guest talk,  Walter!