Lesson 8

Class Party

Est. Class Sessions: 2

Developing the Lesson

Part 1: Planning a Class Party

Discuss Constraints of the Class Party Problem. Display the Class Party page from the Student Guide. Refer students to the problem on the page. Tell them that they will work in a small group to plan a party for 25 students. Read the problem aloud and ask students to raise their hands when you get to a part that is especially important. As you are reading, stop when students raise their hands and ask them to share what they thought was important. Underline and briefly discuss the important information in the text of the problem on the display.

Organize students into groups of 2 or 3. Ask groups to discuss Questions 1–4 in the Student Guide. Briefly discuss responses. During the class discussion students should demonstrate understanding that they are trying to plan a class party for 25 people with a budget of $10. As much of the ten dollars as possible should be spent without going over. Since there is a list of items to choose from, there are many different ways to spend the ten dollars.

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The size of the groups does matter. If groups are too big, some students may have difficulty staying engaged. If groups are too small, there may be too many tasks or not enough people to contribute to the task. For this problem, student pairs or groups of three have been effective.

Questions 1–3 help students form a plan before starting to solve the problem. While trial and error may be a strategy used by many, understanding that they will need to tell what they decided to buy, how much it cost, and why they decided to buy those items will help them include all necessary steps. Tools such as calculators, number lines, and the 200 Chart (Student Guide Reference section) should be readily available.

In addition to the discussion above, also discuss student questions and briefly discuss the following considerations:

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  • Can we give students half of something? (A good rule-of-thumb is that each student needs to get one of each item.)
  • What about extras? (Extras do not matter as long as each student gets one of each item chosen for the party.)

Stress that an important part of this activity is for the team to work together to make these decisions and to solve and write a solution to the problem. Be sure students know where to find appropriate tools.

Discuss responses to Question 4.

Students might come up with a list of items to include in their written explanations like this:

  • What we decided to buy for the party.
  • How many of each item we decided to buy.
  • How much those items cost for 25 people.
  • How much of the $10 is left.
  • Number sentences (vertical or horizontal) that show our calculators.
  • Why we chose that party plan.

Review the items and the cost of the items to be sure students understand the information represented in the table. Review the list of steps you prepared as in Figure 1 to summarize what students are to do.

Groups Solve the Class Party Problem. Display the Math Practices page from the Student Guide Reference section and review Expectations 1–6. Tell students the class will revisit and discuss the Math Practices Expectations after students have solved the problem and written explanations.

Give students time to work on the problem. As students are writing their explanations, encourage them to refer to the Math Practices page in the Student Guide.

Some questions you might use as you are circulating:

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  • What have you decided to purchase for the party?
  • What is that (.99) for? Does it need a label?
  • What did you write down to show how you are going to spend the $10? What you are going to buy? How many? How did you determine the total for each item?
  • What are you going to write to show how you solved the problem so that someone can see why your strategy makes sense?
  • What labels are you going to use?
  • What are you going to write to show that you looked back at your solution to see if your answer makes sense?
  • How did you decide what to serve at your party?
  • If you explored more than one party plan, show me the party plans that you eliminated. How are you going to show why you eliminated them?
  • Did you try another strategy? How did you show that? Why didn't it work?
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An open-ended problem like this provides much opportunity for challenge and support. Challenge students to find the party plan that uses the most of the $10 and has the least amount of extras. The two students in the following example tried to purchase an appropriate amount of lemonade for the class of 25 students. Three pitchers of lemonade was 30 servings, so they decided to make 21/2 pitchers. They then used the remaining money to purchase cups, popcorn, and napkins. Notice that these students also decided to purchase one package of 24 cups rather than the two they needed to serve 25 people.

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Students may write a given number of cents incorrectly by using a decimal point and the cents sign (¢) simultaneously. For example, Manuel wrote “.90¢” instead of “90¢” or “$.90.”

Later, he wrote “.2¢” for “$.02,” incorrectly placing the decimal point. You may want to review the ways to write cents before students begin working on the problem.

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For students you feel are having difficulty with the complexity of the problem you may want to limit the number of Math Practices on which they focus. For example, you could help them focus on knowing the problem [MPE 1] and finding a strategy [MPE 2]; or showing their work [MPE 5] and using labels [MPE 6].

If students are having trouble organizing the different steps of their exploration of party plans, divide a sheet of paper into four sections. Ask students to write what they decided or did in one box before moving on to the next box where they can write their next step.

Discuss Math Practices Expectations. After groups have solved the problem and written their explanations, discuss each Math Practices Expectation and take notes on a display of the Math Practices Notes Master. The notes should help students understand what to look for when evaluating their work or work from another group. See Figure 2 for possible student-generated notes.

Ask:

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  • What did you include in your work to show you know the problem? (Possible response: We used addition or multiplication to find the cost of items and the total cost. We used subtraction to compare the total to $10.)
  • What did you include in your work to show your strategy? (Possible response: We tried out different plans and chose the best one for the party. We used a data table [or pictures, charts, or graphs] to show how we used the information in the chart to find out how much items for the party would cost for 25 students. We showed all of our number sentences.)
  • How did you check and show if your response was reasonable (Possible response: We showed two different plans to see if we could get closer to $10.)
  • How did you check the calculations in your solution? (Possible response: We checked multiplication number sentences by adding [or using a calculator] and we estimated first.)
  • What else did you include in your explanation? (Possible response: We told what we decided to buy for the party and how many of each item we needed. We also told how much of the $10 was left.)
  • What labels should you include in your explanation? (money signs, names of each item bought, titles on tables, pictures, graphs, or charts)
Student Guide: 188
Answers
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SG_Mini
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Student Activity Book:
Master:
Sample class notes for Class Party
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