My husband packs lunch everyday and he has no microwave to heat up the food. Usually, he brings sandwiches and fruit. Sometimes, he would pack homemade pizza or pasta or even salad (suggests to have no sauce or add sauce right before eating) and eat it cold. If you want something hot for your kid, you may consider buying a thermo and cook in the morning. It should be still warm at lunch time. But, for kids in high school, I wonder if they would prefer eating the same thing like their friends do. Maybe you can ask your boy first if he wants you to prepare lunch for him or maybe at least let him choose what he wants to eat for lunch.
花旗太太生活在花旗國,留意時差,你問我未必即時答到。