An electric heater is a device that converts electricity into heat. A commercial version typically produces infrared radiation which is converted into heat when it strikes an absorbing surface. This type of heater may also be known as a space heater because it's designed to heat a specific area, especially when the air itself is cold. You can demonstrate this principle by making a very basic electric heater from common materials.
Cut two lengths of electrical wire with the wire stripper. Strip off approximately 2 cm of insulation from each of the four ends with the wire stripper.
Tape one end of a wire to the negative terminal of the battery with electrical tape. Likewise, tape an end of the other wire to the battery's positive terminal.
Connect each of the free ends of the wires to an alligator clip. Take a handful of steel wool and shape it into a long cylindrical shape. Pull the strands apart slightly to ensure they're only loosely packed together. Place the steel wool in a ceramic plate.
Fasten an alligator clip on each end of the cylinder of steel wool. The steel wool should begin to heat up and may even produce smoke.
Compare this demonstration to a commercial electric heater. A basic commercial heater may use a heating element that consists of several coils (filaments) of thin wire to provide a circuit with high resistance and a high surface area. The resistance is carefully chosen so that's high enough to produce a large amount of heat but not high enough to melt the wires. Furthermore, the coils of wire are typically enclosed in a half cylinder with a reflective surface that concentrates the heat and directs it outwards.