# What's the Difference?

This lesson can be used as a pre-lesson for the Subtraction Card SharksLesson plan.

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This lesson can be used as a pre-lesson for the Subtraction Card SharksLesson plan.

Students will be able to find the difference between two whole numbers by subtracting within ten.

##### Language

Students will be able to describe the steps to solve for the difference between two whole numbers with academic vocabulary using manipulatives, and partner support.

(5 minutes)
• Show students a deck of playing cards and ask them to give a thumbs up if they have seen cards before.
• Tell students to turn and talk to a partner to name a familiar card game. Provide the sentence frame, "I have played the card game ____." If students have never played a card game, instruct them to shake their head no and say, "I have never played a card game."
• Choose a few students to name and describe a favorite card game.
• Describe a deck of cards by writing the four suites on the board with a sketch: hearts, diamonds, clubs, spades.
• Show students a card, for example the two of diamonds. Point out the number two, and count the diamonds.
• Show students the ace of hearts, and tell them that this card is special, and has an "A" instead of a number in the corner to stand for "ace." Ask students how many hearts they see on the card (one).
• Tell students that today they will use cards and counters to play a maths game. The aces will stand for "one" in the game.
(10 minutes)
• Tell students that SubtractionMeans to find the difference between two numbers. The DifferenceIs the amount in which the two numbers are not the same.
• Tell students the story problem, "Kecia and Noah love to read! Yesterday, Kecia read 4 books and Noah read 9 books. How many more books did Noah read than Kecia?"
• Think aloud as you model solving the problem. Ask students to show you on their fingers how many books Kecia read (four). Draw four rectangles on the board to represent the books. Say, "I see the word MoreIn the story problem, so I need to add 4 + 9."
• Allow students think time and an opportunity to correct you. Reflect, "Now I see that I need to solve for how many MoreBooks Noah read ThanKecia, not how many books they read In all.To do this, I need to CompareThe two numbers."
• Ask students to show you on their fingers how many books Noah read (nine). Draw nine rectangles on the board directly below the four rectangles, lining them up exactly so the extra rectangles are clear.
• Ask, "Who read more books, Kecia or Noah?" (Noah.) Say, "This drawing helps me to see how many MoreBooks Noah read ThanKecia." Circle the five extra rectangles.
• Ask if anyone can think of a way to show the difference between the number of books that Kecia and Noah read using a number sentence. Agree that the problem could be solved using subtraction, and write the equation 9 - 4 = 5.
• Tell students to repeat after you, "Noah read five MoreBooks ThanKecia."
• Explain that LessIs the opposite of More.Tell students to repeat after you, "Kecia read five LessBooks ThanNoah."
(10 minutes)
• Tell students that today they will play a game called "What's the Difference?" Explain that the phrase is sometimes used to mean that something does not matter, or is not important. In maths, the difference refers to the amount to which two numbers differ.
• Distribute twenty counters or other maths counting manipulatives to each partnership. Decide who is Partner A and who is Partner B. Ask students what shape the counters are. (Circles.)
• Model the steps to play the game as you write the steps on the board:
1. Partner A chooses a card and builds the number. (Students follow along as you display a card and show that many counters, for example six.)
2. Partner B chooses a card and builds the number, lining up the counters below Partner A's counters. (Display a second card, for example four, and show students how to line up exactly that many counters below.)
3. The partner who chose the greater number says, "____Minus ____Equals __." (Say "Six minus four equals two," and instruct students to repeat after you.)
4. The player who chose the greater number takes the number of counters equal to the difference between the two numbers. (Point to the two extra counters. Think aloud, "The difference between the two numbers was two. Player A takes two counters because Player A chose the greater number, six." Model moving two counters to the side, and putting the rest back in the middle.)
• Play a few rounds as a class. Display two playing cards, one for Partner A and one for Partner B. Check that students accurately line up the counters to solve for the difference.
• Require that the students say a number sentence before they take the counters. Check that students understand that the player with the greater number takes an amount of counters equal to the difference between the two numbers, not the total number of counters.
• Tell students to describe the steps to play the game to a partner using the transitional words first, next, then, and last.
(10 minutes)
• Distribute playing cards to partnerships. Walk the students through one round with each partner choosing a card.
• Circulate and assess that students are able to accurately compare the numbers to find the difference.
• Listen that students are able to say a number sentence that shows the difference between the two numbers.

BEGINNING

• Use cards that show just the numerals 1-10 rather than playing cards.
• Play the game in a teacher-led small group.

• Allow students to write their own word problems that involve subtracting to compare. Allow students to exchange problems with classmates and solve.
• Ask students to describe times when they have subtracted to compare, or find the difference, between two numbers.
• Circulate as students play the game, and check that students are following the steps to play.
• Observe whether students are able to count and accurately line up the counters to solve for the difference.
• Assess that students are able to say a number sentence that includes the two numbers that were chosen, and the difference between the two numbers.
(5 minutes)
• Allow students time to count their counters. The player with the greater number of counters wins.
• Remind students that subtraction can be used to compare, or find the difference, between two numbers.
• Ask students to give a thumbs up if they liked the game. Choose a few students to share an opinion of the game using the sentence frame, "I did/did not like the game because ____."
• Move the game to a centre to allow students more practise with subtraction in small groups. Include the instructions and materials to play the game.

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