Lesson 16

The purpose of this warm-up is to elicit the idea that two true comparison statements can be used to describe the relationship between two values, which will be useful when students write statements using <, >, and = in a later activity.

• Groups of 2
• Display the inequalities.
• “What do you notice? What do you wonder?”
• 1 minute: quiet think time

• “Discuss your thinking with your partner.”
• 1 minute: partner discussion
• Share and record responses.

• “Even though these comparison statements are written differently, they tell us the same information. How can that be?” (One symbol means “greater than” and one means “less than.”)

Students should remove cards that show 10 from their deck.

• Groups of 2
• Give each group a set of number cards and two recording sheets.
• Ask students to remove the cards with the number 10.
• “We are going to learn a new center called Greatest of Them All. You and your partner both make a two-digit number. Try to make the greatest number you can because the player with the greater number wins. Let’s play one round together.”
• Display the number cards and recording sheet.
• Invite a student to act as your partner.
• Choose a number card.
• “I can decide where to place this digit on the recording sheet. This digit can be my ones or my tens, but once I place it, it cannot be moved.”
• “Where would you place this number on the recording sheet? Why would you place it there?” (I would put it in the tens place because 6 is a high number and I want to have a lot of tens. I would put this number in the ones place because I want to try to get a greater number for my tens.)
• “After you place one number, your partner chooses a card and places the number on their recording sheet.”
• Invite your partner to choose a card and decide where they will place the number.
• Repeat until each of you has a two-digit number.
• “Now we compare our numbers. Who has the greater number? How do you know?”
• “Finally, we write a comparison using <, >, or =.”
• Demonstrate writing the comparison statement on the recording sheet.
• “The player with the greater number gets a point. Continue playing until someone reaches 5 points.”

• 10 minutes: partner work time

• Display a recording sheet with a 5 in the tens place for one partner and the rest blank.
• “My partner has a 5 in the tens place. I choose a card and see that it is a 6. Where should I place the 6? Why would you place it there?” (Place it in the tens place because 6 tens is more than 5 tens so the number in the ones place won't matter. You will have the greater number.)

The purpose of this activity is for students to write the symbol or number that makes a comparison statement true. Students then read the comparison statement. This activity has two parts. In the first part, students are given two numbers with a blank space in which to write a comparison symbol that makes the statement true. After students write the symbol, they read the comparison statement. Reading the statement encourages students to relate the language of comparison to the symbols (MP6). In the second part of the activity, students are given a comparison symbol and either one number or neither number. Students determine a number or numbers that will make the comparison true.

• Groups of 2
• Give students access to connecting cubes in towers of 10 and singles.

• Read the task statement.
• 8 minutes: partner work time

If students create statements that are not true, consider asking:

• “Read your statement. How could you prove that it is a true statement?”
• “What other numbers could you use to make this a true statement? Explain how you know.”

• Display \(\boxed{\phantom{3}} > 78\).
• “How did you know what number would make the statement true?” (I knew it had to be greater than 78 because I read the statement ‘blank is greater than 78’. I put in a number and read the statement out loud to see if it was true. I chose a number with more than 7 tens so I knew it would be greater than 78.)
• Display \(39 < \boxed{\phantom{3}}\).
• “How did you know what number would make the statement true?” (I knew it had to be greater than 39 because I read the statement ‘39 is less than blank’. I put in a number and read the statement out loud to see if it was true. I chose a number with more than 3 tens so I knew that it would be greater than 39.)
• Invite students to share comparisons they made for \(\boxed{\phantom{3}}< \boxed{\phantom{3}}\) and \(\boxed{\phantom{3}} >\boxed{\phantom{3}}\).\(\) For each comparison shared, have the class decide if it is true or not.