Ohhh man. This could take two lessons, actually. Make just with pins and cardboard. 

How to do without maths? Could take a few standard linkages and play with them

Standard 4-bar linkage (boom)


Crank and slider linkage

Introduce lever as two-bar linkage?

RESEARCH: Good way to teach about linkages without maffs. Also, to teach 
about linkages in terms of FORCE and in terms of movement paths. 

Also, a good way to design linkages. 

Could split into two lessons, one with a small (controlled) design challenge, and a few examples of linkages, the next lesson, they build their own linkage-controlled object. 

I really need to play around with a lot of lego. Like, a lot of lego.
Grashof mechanisms! Dey cool. 

It is sort of cool to have the kids play around with linkages on a piece 
of paper. 

Instant center. Read up lots on linkage design!

Extending linkages (scissor linkages)

Probably a two-parter

Way to map things. Draw a picture! Spirograph?