Frequency plots or histograms are a very useful visualization tool for univariate data. Wendy Williams of the University of Arkansas collects data on her students, including their shoe size, to introduce them to histograms on the first day of class.
The links below can help your students learn how to understand and create histograms.
Quarknet Histogram Maker: Students can use this Java applet to draw quick histograms of their data.
This applet (more info) is designed to teach students how bin widths (or the number of bins) affect a histogram.
Microsoft Excel has a built-in histogram feature. This tutorial from North Carolina State University can help your students use Excel to create histograms of their data.
This Excellent online data analysis program was used to create the histogram and table of relate statistics for the annual mean temperature in Vancouver, WA between 1895 and 1994 shown below. The Text File of 1895 to 1994 annual average Temperature for Vancouver, WA ( 1kB Jul8 04) was used to paste data into the window displayed after clicking the "Type in Data" button. Students can just as easily type in their own data values.
Click either image below to enlarge.