Demonstrate the presence of electrical current in fruit by first squeezing a lemon with your hands to soften it up and promote the movement of liquid inside the lemon's skin. Insert two-inch zinc and copper nails approximately two inches apart from one another, but not so either nail is touching the other one inside or outside the lemon. Take a small light bulb and strip away about two inches of insulation from the bulb's leads. Wrap one of the leads around the zinc nail and coil the remaining lead around the copper nail, fastening the connections with electrical tape. Now your circuit is complete and your bulb should light. If it does not, check the two connections to make sure your circuit is complete.
Show your elementary students two fully-inflated latex balloons with six-inch strings tied around their necks; hold the balloons only by the strings. Have a volunteer rub each balloon with a wool cloth for five seconds before allowing them to drift near each other; the balloons will repel each other as rubbing them made them both negatively charged. Have a volunteer rub one of the balloons on a classmate's hair vigorously before gently holding it about two inches from their hair; students will note that the classmate's hair is attracted to the balloon as the balloon becomes negatively charged and the hair becomes positively charged. Finally, have a volunteer rub one of the balloons on another child's hair before laying an aluminum can on its side and passing the balloon within a few inches of the can. The can, which has become positively charged, will be attracted to the now negatively charged balloon.
Take three six-inch pieces of copper wire and strip an inch of insulation from both ends of each one. Attach one piece of copper wire from the positive side of a nine volt battery to the right side of a small light bulb using electrical tape or crocodile clips. Take a second copper wire and run it between the negative side of the nine volt battery and the left side of a switch. Complete your circuit by affixing the right side of the switch to the left side of the light bulb, which will ignite when correctly attached. Encourage your youngsters to utilize the circuit's switch and, using a fourth six-inch piece of copper wire. Challenge your students to add a second light bulb into their circuit.
During all science experiments, and, in particular, those that involve handling electricity, health and safety should be paramount. Although your youngsters will only deal with safe, very low levels of electric power, you should still use this as an opportunity to acquaint them with safe electrical practices, such as only handling electronic goods with one hand at a time, limiting the potential for an electric shock to pass through a scientist's chest. For a fun and simple activity, split your class into groups of four, teach them each a rule of the electricity laboratory, such as always wear rubber gloves or never run in the electricity laboratory and have them design a poster to pin on the notice board explaining the importance of their rule.