Science Buddies: "Ask an Expert"

Well I have no idea how I am supposed to use standard deviation on my project. I will explain it and put up my data table for you to see and better understand. Please respond asap as its due Monday. Ok, so I tested how lenses would affect electricity output of a solar panel. I placed a lamp above a solar panel, then tested using different sets of lenses in-between them to see how it affected the electricity output. I did 3 trials for 6 types of lenses. I measured volts and amps. My teacher says we need to do standard deviation. She also said we need to make charts of our averages. So what i first did was make a chart with the averages of the 3 trials for each lens type. I made one for volts and one for amps. But then i attempted to learn and incorporate standard deviation bars, and i came to the conclusion that i would need to make two charts for each lens type, volts and amps due to what standard deviation is. Can someone either confirm this, or tell me how i could do standard deviation on my first charts, the ones with the averages of each lens type. If you can do neither, then please explain in a fairly simple way how i would make charts with standard deviation for my data. Please Please Please respond asap.

Sorry to tell you this, but to get a meaningful standard deviation you would need at least 10 trials. Formally, you can compute a "standard deviation" with three samples, but it would be MEANINGLESS. A better measure of the estimated error would be the size of the largest deviation of your three samples from the average. That is if your values were
a, b, and c, then the the average = (a + b + c)/3. Calling the average d, the deviations would be a-d, b-d, c-d and the error estimate would be the largest of the three deviations.