How does a picnic cooler work?
What kinds of food can you take on a picnic? Any kinds you like—hot
baked beans, steaming cocoa, chilled potato salad, or ice- cold
lemonade. You can put the food in a picnic cooler, or in special dishes
or bottles, to keep it cold or warm.
Foods packed in these special containers are insulated
[(ihn]{.smallcaps} suh layt uhd). They are surrounded by layers of
matter that keep heat in or out.
Some kinds of matter, such as aluminum, steel, and other metals, conduct
heat very well. Their molecules move very easily and pass the heat
along.
But other kinds of matter have molecules that move very little. They
conduct heat very slowly—so slowly that sometimes they hardly seem to
carry heat at all.
Materials like wood, cork, and plastic foam don’t conduct heat very
well. So containers made with these materials are used to slow
down heat! When you pack hot food in an insulated dish, it loses heat
very slowly. And when you pack cold food in a picnic cooler, the heat
from the outside air takes a long time to get in.
The same kinds of materials are used to
weather, the insulation slows down the heat going out and helps keep
buildings warm. And in hot weather, insulation slows down the heat
coming in and helps the houses and buildings stay cool.
insulate houses and other buildings. In cold
Materials
aluminum foil
a glass marble
paper
a penny
plastic foam cup
a quarter
scissors
a wooden button
