Use an old telephone book.

Distribute different pages from an outdated directory to pairs of children.
Ask the partners to underline 40 telephone numbers.

Tell them to add the last two digits in each of the 40 phone numbers (example: 639-4968; 6+8=14)

Then students construct a tally sheet indicating how many of each sum (from 0 to 18) they find.

One partner uses the information to plot a bar graph while the other creates a line graph.

Ask each student to check the other's work for accuracy.