1. February 26, 2009 Can you do Division? Divide a loaf by a knife - what's the answer to that? ~Lewis Carroll, Through the Looking Glass

2. February 26, 2009 Section 3.4 – division Exploration 3.15 Videos Homework

3. February 26, 2009 Test 2 – Thursday, 3/12 (50 min.) Covers: Text 3.3 & 3.4 (Multiplication and Division) Explorations (so far, 3.13 and 3.15) Class Notes

4. 3.4 – Understanding Division Explain what is wrong, and why it’s wrong: “50 ÷ 7 is the same as 50 ÷ 10, which is 5. But, I added 3 to the divisor, so now I need to subtract 3: 5 – 3 = 2.”

5. 3.4 (cont’d) Multiplication and Division In mathematics, we say that addition and subtraction are inverse operations. This is why there are related facts: 3 + 4 = 7; 7 – 4 = 3; 7 – 3 = 4 In this same way, multiplication and division are inverse operations: 3 4 = 12; 12 ÷ 4 = 3; 12 ÷ 3 = 4

6. 3.4 (cont’d) Exploration 3.15 On your own, make up a story problem for: 15 ÷ 3 As a group: Share your problems. Sort into two or more piles. Select one from each pile and write it on the chart paper.

7. 3.4 (cont’d) Vocabulary: In any division problem, dividend ÷ divisor = quotient In word problems, we usually have a rate as part of the problem (e.g. apples per person). Where the rate appears determines the type of word problem.

8. 3.4 (cont’d) Where is the rate? 1.Jack has 18 books. If he stacks 3 books per pile, how many piles of books can he make? This is repeated subtraction. 2.Jack has 18 books. If he wants to make 3 stacks of books, how many books will be in each stack? This is partitioning.

9. 3.4 (cont’d) Turn to Class Notes pg 11. Take notes that will help you remember each child’s strategy.

10. 3.4 (cont’d) With your table, discuss questions 5 – 8 on pg 13. (Cross out the sentence about “Shannon” in #6). When finished, move on to pages 14 and 15. These will be collected on Tuesday.

11. Homework Due Tuesday, 3/3: Link to online homework list