When doing labs in the classroom, I need to be prepared to the nth degree. With the limited amount of time during a class (for setup, experiment, clean-up), for a smooth lab I need to be very organized. In fact, I do the lab myself ahead of time; I figure out what can go wrong, and then fix it before it gets to the kids. Actually, most of the time, I can't even predict what will go wrong when the students start playing around with the equipment, so I have to be flexible, very decisive when the time comes for the unfortunate event of a problem. In fact, things going wrong is a good thing. This is science, and when things go wrong, new discoveries are made.

For example, today we had a lab on electrostatics. I prepared and tried the lab ahead of time, had everything ready, stations with balloons, with vinyl, PVC pipe, glass rods, acetate strips, silk, cotton, fur, graphite balls - the works! I've done this lab several times before - it's a good lab, makes the point of like charges repelling and unlike charges attracting very well, and kids love it (usually).

Today we start working on the lab - nothng works. I can't believe the kids when they tell me, so I go and try rubbing the PVC pipe myself: I can't believe my eyes: no reaction, no repelling, no attraction. I go to the next station: the two acetate strips are not repelling... the graphite ball is just hanging, not the usual "electrostatic dance". As a physicist, I think hard and fast to explain this phenomenon. I need to understand myself - it's fascinating, and I never saw this before - but also I have to explain to my students who are trying to do a simple lab on static electricity and nothing is working. After a quick scan of my brain, I remember that static electricity works best when the air is dry not humid. Realizing that it is raining outside, I quickly tell my kids that because the air is humid, objects can't be charged easily, therefore the experiment is not working properly. That satisfies some of them, but not me... why is this so? How come I never asked that question before? Why is static electricity only happen in dry conditions? I am ashamed that I can't explain this simple effect: As soon as I have some free time, I search for the answer:

You notice static electricity much more in winter (with clothes in a dryer, or taking a sweater off, or getting a shock when you touch something after walking on carpet) than in summer because the air is much drier in winter than summer. Dry air is a relatively good electrical insulator, so if something is charged the charge tends to stay. In more humid conditions, such as you find on a typical summer day, water molecules, which are polarized, can quickly remove charge from a charged object. Information provided by: http://physics.bu.edu

Makes sense, right?

But in the mean time, I also found these other interesting questions on static electricity (maybe you have some answers to these observances):

1. Why do some people get overly charged while others do not?

2. I came across a friend who was so charged that if he touched anything he would get a severe electric shock. I asked him to drink more water and his condition decreased! What is the scientific reason for this?

3. Oftentimes disturbed or excited or tense people are prone to be more charged. Why?

4. I met a person who got charged within minutes and if somebody touched him, they got a severe electric shock. I found that if I continuously hold him he could not get charged. However, as soon as I left him isolated, he gets so charged that one could see arcing, even from his ear! What is the reason for this person to have such physiological behavior?

5. I know of an electrical contractor who was having such a problem for the past ten years. The last time he came to my office, he shook the hand of a fellow worker who was thrown 10 feet away by the electric shock. I asked him to change his clothing material and drink more water. I have not spoken to him since, so I do not have the results.

6. My son gets charged when he is inside the car with the hot air on. I used to get a shock when I was leaving my apartment in Schenectady, NY when I was in GE training. Most of the people get a visual electrostatic discharge with a mild hissing sound when they take off their clothes, especially woolen or polyester.

7. I have no idea why, but I have gotten shocked on a trampoline when it has been exposed to the sun.

8. My wife gets very electrically charged (polyester clothing sticks to her body) during part of her menstrual cycle.

9. I have heard rumors that some factors in the 1950's actually reduced production of sensitive electronic equipment because the women on the assembly line became concurrent with their menstrual cycles!

Note: I did speak to some on this topic and the comment was that women's skin dries out during part of the menstrual cycle and the rubbing of the skin with the polyester clothes created the triboelectric effect. Made sense to me.

Source: http://www.mikeholt.com

If not for this mishap, would I have found all these cool facts about static electricity? The students will have a great understanding of this phenomenon, because they experienced it first-hand. Could I have planned it better? I can redo the lab tomorrow (as a demo) with dry conditions...

Another tip I've discovered: have fun, because that's what labs are about... If it turns out that something looks rediculous or "perverted" for the teenage mind, I laugh WITH my students. Actually I like when something is funny... it's a way to break the ice, get the non-scientist kids interested, if it is only for the sake of the joke (rubbing a pipe with a cloth back and forth brings impure thoughts into teenage boys' minds).