By Carla Bridges

 Investigate and describe that without touching them, material that has been electrically charged pulls all other materials and may either push or pull other charged material.  Taken from: /sci/sci_4_3_16.pdf /sci/sci_4_3_16.pdf

 Students will be able to demonstrate that without touching them, charged materials may be pushed or pulled by material that has been electrically charged.

 For the teacher:  2 balloons  2 lengths of string 3 meters long  Felt tip pen  Adhesive tape  Wool cloth

 Inflate one balloon and hang it from the doorway about eye level with the students.  Write definitions of the following on the board. Discuss before putting the correct definition.

 Static electricity- a stationary electric charge built on a insulating material. Positive and negative chargesPositive and negative charges  Each atom is made of a nucleus which has a positive electrical charge. Electrons move around the nucleus. They have a negative electric charge.... The positive and negative charges cancel each other out.  Repel- to drive or force back.  Attract- to draw by a physical force causing or tending to cause to approach, adhere, or unite; pull.

 Ask students: “What is static electricity? Give examples of when you witnessed static electricity.” [Clothes that cling when coming out of the dryer, etc.]  Explain to students that almost all things carry a small electric charge and that objects and organisms carry two different kinds of electric charges − positive and negative.  Tell students that if two objects are near each other and they have the same kind of charge, they will repel or move away from each other. However, if two objects are near each other and they have different kinds of charges, they will attract or move toward each other.  4. Ask students: “With this new information, can you think of a time when you have seen this happen?”

 1. Direct students’ attention toward the balloon you fastened.  2. Ask students: “Have you ever witnessed a balloon having static electricity?” Briefly discuss students’ responses.  3. Ask a volunteer to rub the face of the balloon with a wool cloth.  4. Ask students: “What is happening?” [The balloon should face the student and move toward him/her.]

 Tell students that by rubbing wool cloth on the balloon, they are creating static electricity. Remind students that rubbing two objects against each other creates friction. Tell students that the friction causes a static charge. (The friction causes a transfer of electrons, which creates the charges.)  Ask students: “Why is the balloon moving toward [insert student’s name]?”  Discuss how the student and the balloon are both electrically charged but must have opposite charges, since the balloon is attracted to him/her.

 Ask a volunteer to inflate a second balloon and tie the balloon with string. Hang the second balloon near the first balloon.  Ask a volunteer to rub the balloon with wool cloth. (The student may have to “recharge” the first balloon.)  Tell students to stand back and observe the two balloons. Ask: “What is happening?” (Students should observe the two balloons moving away or repelling each other.)  Ask students: “Why are the two balloons repelling each other?”  Discuss with students how the two balloons are repelling each other so they must be carrying the same kind of charge.

 After the class has completed the activity, ask students:  What causes static electricity?  Why did the first balloon move toward you?  Why did the two balloons move away from each other?  How do you know when two objects carry the same kind  of charge?  How do you know when two objects carry opposite charges?

 Begin a class discussion of how society depends on electricity. Have students make a list on the chalkboard of ways they depend on electricity every day.  Have students write stories on what their lives would be like every day without electricity.  Language Arts Standard

 Standard Indicator /sci/sci_4_3_16.pdf /sci/sci_4_3_16.pdf  Dictionary.com  Science.com