Saturday, February 18, 2012

Adding Three or More Numbers: Dominoes, Dice, and a Deck of Cards

Day 1: Dominoes

Tell the students that we appreciate how hard they've been working, so this week, we're going to play with dominoes, dice, and a deck of cards.

Give each student a copy of the domino addition page and pencil. Each student then selects a domino and writes the number sentence for their domino at the top of their paper in the "My Domino" section. (Example: 2 + 6 = 8) Review the commutative property and ask students to write another number sentence for their domino. (Example: 6 + 2 = 8)
Tell the students that now that we're so good at adding two numbers, we're going to start adding four or more numbers together. Put the students (and their dominoes) with a partner and have them write as many number sentences as they can for the two dominoes put together in the "My Partner and Me" section. Hopefully each pair will end up with LOTS of number sentences (up to 24), but the sum of each should be the same.

2 + 6 + 1 + 3 = 12
2 + 1 + 3 + 6 = 12
1 + 2 + 3 + 6 = 12 etc.

Now divide the students into two groups and have them add the sum of all their group's dominoes by writing it in a number sentence in the "My Group" section. (Example: 2 + 6 + 1 + 3 + 4 + 0 + 8 + 5 = 29) Ask students to describe how they came up with the answer.
Finally, help the students add up the sum of ALL their dominoes in the "The Whole Class" section. Review the concept of counting on, and demonstrate how this is a useful way to complete this problem. If there's time, try different ways of getting to your grand total such as having them add to their partner, then finding the sum of these pairs of dominoes.

Day 2: Dice

Pair students up with a partner. Hand out two dice and the worksheet Missing Addend – Dice to each pair.
Explain to the students that the magic number today is 12. The answer to all the addition problems on this worksheet is 12! To complete the worksheet they will first fill in the blank for the sum (12!), and then they will roll the dice and record the number of dots for each dice in the space that looks like dice. The sum of the dice will be recorded on the line above the picture of the two dice. The students will then solve the addition sentence for the missing addend. The missing addend will be recorded on the worksheet in the missing addend symbol. (Do an example for them on the whiteboard before turning them loose.)

Day 3: A Deck of Cards

Today we're going to play a card game to find our three-number addition champion! Divide students into groups of three. The three players divide the cards evenly among themselves.
All players turn over a card at the same time. The first person to correctly add the numbers on the three cards and say aloud the correct sum collects all three cards.
In the event of a tie situation where all three players give the answer at the same time, all players keep their own cards.
If two players say the answer at the same time, they keep their own cards. The third player's card is removed from the game.
Play continues until one player loses all of their cards. The other two players count their cards to determine a winner. The player with the most cards is the winner.
Mix up the groups and play again as time allows.

Bonus Game (or Day 4): If there is extra time any of the days, play the following game:

Put the students in partners. Each pair will face each other and put both hands behind their back. When the teacher says go, each student will show their hands, showing a number of fingers (1-5). The student who can correctly give the sum of the four hands quicker wins that round. The students who did not win will take their seats and the remaining students will pair up with the student closest to them and play the game again. The game is played until one student remains.

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