Draw a a four-line pictograph, using dry-erase markers on a dry-erase board, with one line in each color for dog, cat, bird and fish. Survey the class and put a smiley face on the correct line for each student's favorite pet. Students then count how many smiley faces are in each category.
Draw a bar graph with a vertical line intersected at 90 degrees at the bottom by a horizontal line. On the horizontal line, use the dry-erase color markers to label the four categories of cat, dog, bird and fish. Number the vertical line, starting with "1" at the bottom and moving up the line to the highest number needed for any category. Use corresponding color markers to draw lines up to the appropriate number for each category taken from the pictograph.
Draw a pie graph using a circle on the board. The pie will be cut into four "pieces" representing the cat, dog, bird and fish votes. Use the same color for each category as the pictograph and bar graphs. The size of each piece will be determined by its percentage in relationship to the total number of votes. For instance, if 10 students out of 20 students vote for "dog" as their favorite pet, that piece will take up 50 percent of the total circle, or "pie."
Ask the students to compare the three different graphs. Have them tell you how many dogs were voted for while pointing at the pie graph. Ask them how many cats were voted for while pointing at the bar graph. Same, too, for the pictograph. Keep repeating, back and forth, using one graph and then the others.
Deepen their comparison skills. Draw new pie and bar graphs on the board. One should represent the favorite pets in your class and the other for the favorite pets in another class. The numbers should be different. Ask the students questions about each graph, so they're able to read each graph. Ask questions that involve comparison. Have students tell you which class has the most birds, cats, dogs and fish.