The picture shows a collection of data spread out upwards so you can see the individual points. The mean is shown by the red line and the standard deviation is shown by the blue arrows.
You can move the points back and forth and see what happens to the mean and standard deviation.
You can change how many points are in the data set by moving the slider up and down.

1. What happens to the mean and standard deviation of you move one point far out from the rest? Is the effect the same for different sample sizes?
2. For any particular sample size (say 20), how can you move the points so that the standard deviation increased but the mean stays the same?
3. For any particular sample size (say 20), how can you move the points so that the mean increases but the standard deviation stays the same?