Addition: Over in a Flash
Students will be able to find two numbers that equal a certain sum.
- Start the lesson by having students in the class take turns finding the Sum, or the answer to an addition problem, of numbers on addition flashcards.
- Tell students that next they will see the sum of an addition problem on an index card, and they will need to come up with two numbers that, when added together, equal that sum.
Explicit Instruction/Teacher modeling(5 minutes)
- Split the class up into teams of four or five students.
- Hold up an index card with a number on it so that all students can see it.
- Have one student from each team try and come up with two numbers that would add together to make the number on the card.
- Model coming up with two numbers that, when combined, equal the sum on the card. Think aloud as you figure out the two numbers, referring to manipulatives as necessary. Ask the students to think about other number combinations that would equal the sum on the card. Elaborate that it is possible to find different sets of numbers that equal the same sum. Provide students with an example.
Guided practise(10 minutes)
- Assign one person to keep score for the whole class, whether it be yourself or a student.
- The person who says a correct combination first gets awarded a point for their team. The team with the most points at the end of the game wins.
- Play the game until you have gone through all of the index cards.
Independent working time(10 minutes)
- Split students into pairs.
- Divide the stack of cards up into equal piles, one pile for each partner pair.
- Have students take turns coming up with different number combinations for the sums on the index cards.
- The pair who goes through the whole stack correctly first wins.
Enrichment:Have students come up with a combination of three numbers that add up to the sum on the index card, or have students come up with subtraction problems to equal the number on the index card.
Support:Have students use a number line, a number chart, or blocks to physically see the numbers they are adding to make the sum.
- Students could get additional practise by playing BrainzyGames.
- Observe students' answers in the games, and take note of any students who appear to be struggling and in need of more practise.
Review and closing(5 minutes)
- Bring the students back together and write a number on the board.
- Pass out whiteboards and whiteboard markers to each student.
- Give the students a few minutes to come up with as many two or three addend combinations as they can that equal the sum on the board.