Bar Graphs
Invite the students to name the different ways potatoes can be prepared. (The lesson begins with the collection and display of qualitative, that is, nonnumeric data.) Choose four of the ways to prepare potatoes (for example: French Fries, mashed, potato, or baked), and have the
students write their favorite way from among those four on an index card. Draw a line on the floor (Various surfaces require different tools for denoting a line on the floor. Tape may be used on carpet. An erasible marker might be used on vinyl flooring.) Label four points, one for each way. Then ask the students to form lines behind the choice that they have written on the index card. Call on a
volunteer from each line to count the students in that line. Now ask the students to step aside and make a column with their index cards, laying them flat on the floor. Ask the students to stand in a ring around the graph and notice
how their cards take their places to form a graph. Instruct the students that they will now record their preferences in a bar graph by recording each card with their names on a set of axes you have drawn on the board.
Now ask the students to title the bar graph and to notice which choice was most popular. Tell them that the most frequently selected item is called the mode. [In the example above, French Fries was the most frequently selected item.] Next, give them graph paper, and ask them to copy the bar graph from the board. Encourage the students to take turns asking questions that can be answered by
looking at the bar graph and calling on classmates to answer the questions.
Circle Graphs
To prepare for this activity, cut four lengths of yarn that are five to six feet long. Now ask the students who picked salad to stand beside each other. (Give the last person in that line one end of a long piece of yarn. Place the other end of the string at a point that will become the center of a circle graph.) Have those who chose French Fries line up beside those who selected salad and give the last person a second piece of yarn. Repeat with the other two groups.
Now ask the last student from the last group to walk around to make a circle by standing next to the first student who got in line. Stand in the middle of the circle and hold the other ends of the yarn lengths. Tell the students they have
now made a circle graph or pie chart. (Students will form the circle with the last student in a particular category holding one end of the yarn and you will hold the other end of the yarn while standing in the center of the circle to
complete the pie chart.) Next, invite the students to notice which part of the circle is the largest. Ask them how this compares with the bar graph. Then ask them how they could find the mode for this data set. [It will be the largest sector.]
Next, log on to the National Library of Virtual Manipulative's Pie Chart. Call on a volunteer to enter the data from the bar graph of potato preferences. Then select a student to click on the "Draw Chart" command. Ask the students to share what they can learn from the chart about the potato preferences represented in the room. Now tell the students your preference and ask a volunteer to change the graph so that it now includes your preference. [Although students at this level may not be able to understand the percentages shown on the pie chart, they might enjoy seeing this popular graph. Pie charts, or circle graphs, are helpful in showing the relationship of a part to a whole or the relative relationships among parts.]
Now ask the students to sketch the pie chart and compare this forms of representation with the bar graph that they made earlier in the lesson. [A bar graph is a graph that uses bars to show data whereas a
pie chart uses sections of a whole to show data.] Next, ask the students to visit the Create A Graph web site, choose "Bar" as the type of graph, and enter the data for the potato preferences. Print out the bar graph to pass around while you ask the students how the bar graph is similar to, and different from, the circle graph.
To provide a record of the lesson, ask the students to staple together their bar graph and circle graph of potato preferences and to write two questions that can be answered by looking at these representations. When they have done so, call on individual students to read their questions for the rest of the class to answer. Then collect these papers for the students' unit portfolios.
