Will food heat up more quickly in an aluminum box or a wooden box? Why?
Aluminum is a very good conductor of heat and wood is a very poor conductor of heat. If the heat source is inside the box with the food, it will heat quicker in a wooden box. If the heat source is outside the box it will heat quicker in an aluminum box. Having a glass top would be equivalent to having the heat inside the box so a wood box with a glass top will make a better solar heater.
If all of the heat transfer is from the sun through the open top, a wooden box would keep the heat in, acting as an insulator. The aluminum box would quickly radiate away any trapped heat. If the heat is coming in through the walls, then aluminum would conduct the heat better. A glass top would definitely allow the sun's energy in while trapping the heat. That is how a greenhouse works! The aluminum vs. wood discussion still holds, wood is better in this situation.
solid aluminum. this is because aluminum absorb more heat than wood and this heat is then transferred to the food.