Circuit

​In fourth grade, you identified common materials that conduct heat well or poorly. For example, most pots and pans are made from metal. Metal conducts heat well, making them perfect for cooking things in. The handles are made from plastic: plastic conducts heat poorly. Plastic handles protect your hand from getting burned when picking up a hot pot.

​Some materials conduct electricity well and some do not. Metals conduct heat well, and they also conduct electricity. This is why most wires are made from copper, a common metal. Plastics do conduct heat well, and they also don’t conduct electricity well either. This is why the wrapping on most wires is made from rubber and plastics. Just like the plastic handle on a pot protects your hand from a burn, the wrapping on a wire protects you from an electric shock. This is why worn wires (like charging cables) should never be used.

​Another common material that conducts both heat and electricity very well is water. When you do touch something hot, you run water over your hand to carry the heat away. Water conducts electricity easily. Devices that use electricity should never be used near water. A hair dryer is a common device used in a bathroom. It should never be used near water, and the plugs in bathrooms have special switches (the red and black buttons on the outlet) that will turn the outlet off if an appliance touches water.

​In this picture, we can identify a red wire and a black wire. The wires are wrapped with a rubber insulator to prevent shocks. The wires are colored red for the positive or + wire, and black for the negative or – wire. The end of each wire is stripped of its insulation, so that the copper wire itself can be connected to an input or an output. One important safety note: when wires are connected to a source, such as a battery, they must never be touched together. Doing so can result in injury or damage.