i was going to do something similar -
first i was going to do solargraphs,
then lumen print/photograms with my 5th grade daughter's art class
then i settled upon cyanotypes ... it doesn't take long to make them
and unlike lumen prints or solargraphs, the kids can take something home with them in the end !
in camera lumenprits with a regular camera and lens on "B" takes about 30-45mins at least and then you are left with an ephemeral image ...
cyanotypes just need water ... and they will last forever ...
our first try didn't work last week ( too gloomy not enough UV ) next week will be sunny
and perfect !
( if you don't have cyanotype chems to coat your paper yourself, you can get a "sunprint kit" from an art supply house
or freestyle )
have fun !