Histograms

Move the "size" slider to select a new sample size.
Move the "seed" slider to select a new set of data.
Move the "class" slider to choose a different number of classes.

The applet randomly picks a number between the lower bound
and the upper bound as the class width. Since the applet can
work with any number equally well, it doesn't care what number
is picked.

People on the other hand usually prefer simpler numbers with
few decimal places for constructing frequency distributions.
You should keep this in mind when constructing your own
frequency distributions.

David Gurney, Created with GeoGebra