The purpose of this activity is for students to use a bar graph to compare two quantities and describe the methods they use to find the unknown difference. Monitor for students who draw on the graph and describe ways of finding the difference by counting on or counting back. If students draw on their graph or do not discuss both counting methods during the activity, create and display work so that each method can be discussed during the Activity Synthesis. The discrete segments of the bar graph are used to elicit these counting methods (MP5). However, some students may use addition or subtraction, including known sums, to find the difference. Encourage these students to connect their methods to the counting methods shared in the Activity Synthesis.

• Invite previously identified students to share how they found the difference. If methods are only explained verbally, consider asking, “Can you show us on the bar graph how you could count on (or count back) to find how many more?”
• Record student methods with an equation. For example, for students who describe counting on, write “’.”
• “How are their methods similar? How are their methods different?” (One method starts with the smaller number of pets and counts on to the larger number, like adding 9 more. The other starts with the larger number of pets and counts back to the smaller number, like subtracting 9.)

The purpose of this activity is for students to use graphs to make comparison statements and solve Compare problems. Students represent their comparisons with equations. In the Activity Synthesis, students connect the graph, their comparison statements, and their equations.

When students describe how they see their equations in the graph and how their equations relate to the context, they think abstractly and quantitatively (MP2).

• “How did you decide which group had fewer?”
• “Where do you see this on the graph?”

• Invite 1–2 previously identified students to share their statements using fewer and one equation. (There are fewer pugs than bulldogs. There are 12 fewer. )
• Record equation.
• “What other equations could we write to show how many fewer for _____’s statement?” (We could use subtraction. shows you can count back 12 from 20 to get to 8.)  
• Record equations.
• For each equation, ask, “What does each number represent in the equation?” (20 represents the number of bulldogs. 8 represents the number of pugs. 12 represents how many fewer pugs.)