• Once again generate a distribution of sample means, where each sample has %n1% observations.
• Now select the t-statistic radio button.
• Then check the box to Overlay t Distribution.
• Enter the observed value of the t-statistic for your class data and press Count.
• Include a screen capture of the shaded null distribution in your lab report.  

It's very subtle, but you may notice that the theoretical t distribution has a little bit "heavier tails" than the normal distribution would.