Abstract
This vignette presents an in-class demonstration to introduce the notion of standard error. The students must be able to compute means using SPSS. They must also be able to eye-ball standard deviation from a list of numbers. In doing the activity, they will be exposed to sampling. The demonstration uses a random number generator so that each student faces a different dataset simulating IQs from a single group of participants. Factors affecting standard errors (sample size and population variance) are explored. Finally, the actual formula for standard error is then compared to the roughly estimated standard deviation of the sample means..