Introduce kids to LEDs by asking them to make a greeting card that lights up. This simple project only requires some card, crayons and some different colored LED lights attached to a small battery source. Instruct the children to design a card design that will enable the LEDs to be used most effectively. For example, a village where the LEDs are used as street lights. Once the design has been finished they will need to cut out the areas where the lights will go. Next attached the lights from the inside sticking the batteries to the inside of the card with some tape.
For this project, you need an LED, a strong rare-earth magnet, a lithium battery and some strapping tape. Firstly ask the children to test their LED works by pinching the anode (longer LED lead) to the positive terminal and the cathode (shorter LED lead) to the negative terminal. Then instruct them to cut 7 inches of strapping tape and tape the LED to the battery making sure it is as tight as they can get it. Once the tape has gone round the battery three times they should then place the magnet onto the positive terminal of the battery and continue to wrap. Both the LED and the magnet should then be firmly attached to the battery. Now that the throwie has been made, instruct the children to throw them onto a ferromagnetic surface so that they can see them stick - this is more impressive if done in the dark.
To illustrate just how little energy is needed to light an LED you'll need two potatoes, an LED bulb, 2 galvanized screws, 2 copper coins, and 3 connecting copper wires connected with alligator clips. Insert a coin and a screw into both sides of the potatoes. Connect the copper coin in one potato with the screw in the other with the use of the connecting wires and then the coin in the other potato with the screw in the first one. Connect the last wire to this final coin and the other end to the LED bulb. It should light up showing that the small amount of chemical energy within the potatoes is enough to power the LED bulb.
To create a simple electrical circuit to light an LED students will require a circuit board, a 9 volt battery, an ohm resistor and two pieces of wire. Attach the first wire around the positive terminal of the battery and the other end into the hole on the circuit board. This can be found in the first column in the first row. The first end of the ohm resistor should then be placed into the same first row, but on the second column while the second end should be inserted into the hole on the second row in the second column. Follow this by placing the long wire of the LED into the hole in the third row and second column and the short wire into the third row and third column. Once this has been completed, the students should then connect the second wire to the negative terminal of the battery with the hole in the fourth row and third column. Energy from the battery should flow into the LED lighting it up.