Not being a smart a$$ here, but go to radio shack and buy a solar ciggarette lighter and stick a marshmellow on it instead of a ciggarette
Or get a good magnifing glass and rotate the marshmelow under it. If it can set wood on fire it should cook a marshmellow.
Actually those should work, but he might not get that great a grade on it. Basically I think take a rounded mirrored object prop it up facing the sun then see where the focal point is, the brightest hottest spot in front of it. Then hold the marhmellow on a stick into that point or make a mount to hold it there like maybe a bent coat hanger.
Kinda getting back to the ciggarette lighter again I first mentioned, see I said I wasn't be a smart a$$ about it
For materails to try, I think the bottom of a coffee can rounded into sort of a shallow bowl shape might work. I use those for alot of things, I drink lots of coffee! Beware of sharp edges though.
Maxwell house cans now have a mylar type pull off plastic cover on the top under the plastic lid, no need for a can opener now. I think those were pretty shiney and may reflect well but never tried them. Haven't seen one for ahwile, I think that's what they are. Wife and kid opened the last few cans of coffee.
A shallow stainless steel bowl polished like chrome might work well also.
Don't really want the sides in the way, I don't think they would be of any use, but a rounded curved type bottom should work nicley.
Maybe the aluminum foil type pie pans like store bought pies or pie crusts come in.
Could fold up tin foil to make a little oven barely bigger than the largest marshmellow he would be using, use a magnifieing glass on the side towards the sun to heat that side and the cupped bottom as a solar reflector to concentrate the heat to the bottom of the oven and bake it maybe. If that works he could try making larger ones and squash a marshmellow between a grahm cracker and a chunk of chocolate and makes smores!!
Using a foil pie pan fold it into a box with out the top, place marshmellow inside and cover box with glass to bake it. Probably would be better if foil was painted black and maybe tape some cardboard around all sides of the box for insulation to hold in heat except the top of course. If painting use something non toxic also of course.
Many ideas pop to mind for this, gee I wish my daughters science class would actually try to do something for any type of real science project like this. Maybe for highschool next year?? Most the grade school projects were nice but a dud as far as actually doing anything, and 7-8 grades don't even do any.
