To see who can spot the greatest number of certain animals, Mrs. Kawalski’s third-grade math class holds an addition contest at the circus.
- Alyssa counts 3 elephants in the near ring and 6 elephants in the far ring. How many elephants does she see in all? (3 + 6 = 9)
- Susan, sitting on the other side of the auditorium, spots 6 elephants in the near ring and 3 elephants in the far ring. How many elephants does she see in all? (6 + 3 = 9)
- Who sees more elephants, Alyssa or Susan? (They both see the same number, 9.)
- George focuses on the monkeys, which are his favorite animals. In the first act, he spots 20 monkeys, and in the second act he sees 30. How many monkeys does he see in all? (20 + 30 = 50)
- At intermission, the ticket taker tells Mary that there are 200 people in the animal tent and 300 people in the trapeze tent. How many people are at the circus? (200 + 300 = 500)
- John likes the clowns. He sees 15 red-haired clowns, 3 blue-haired clowns, and 0 green-haired clowns. How many clowns does he see in all? (15 + 3 + 0 = 18). Tell students to approach the problem one step at a time. They can find the solution to 15 + 3 by counting on (15 + 3 = 18) or by adding (5 + 3 = 8, and adding 10). Then use the Zero Property to determine that 18 + 0 = 18.
Alyssa 3 elephants in the near ring + 6 elephants in the far ring (9 elephants in all) | Susan 6 elephants in the near ring + 3 elephants in the far ring (9 elephants in all) |
3 + 6 = 6 + 3
They both see 9 elephants, though in a different order. Review the problem, and write out both equations to emphasize the Order Property.