1ABCWhy are muliplication and division done before addition and subtraction.pptx
•Als PPTX, PDF herunterladen•
1 gefällt mir•320 views
Empfohlen
Weitere ähnliche Inhalte
Was ist angesagt?
Was ist angesagt? (20)
Andere mochten auch
Andere mochten auch (17)
Ähnlich wie 1ABCWhy are muliplication and division done before addition and subtraction.pptx
Ähnlich wie 1ABCWhy are muliplication and division done before addition and subtraction.pptx (20)
Mehr von OER Commons
Mehr von OER Commons (20)
1ABCWhy are muliplication and division done before addition and subtraction.pptx
- 1. a. 3 + 7 • 5 b. How much money would Luz have if she had 3 pennies and 7 nickels?
- 2. Why are multiplication and division done before addition and subtraction?
- 3. Using context, how can this equation be made true? 2 + 8 = 28
- 4. Using context, how can this equation be made true? 2 + 8 = 28 2 tens + 8 ones = 28 ones 2 dozen + 8 halves = 28 ones
- 5. How do you go about adding … 2,416 + 753 = Would you rewrite it or imagine it vertically? 2416 + 753 2 thousands + 4 hundreds + 1 ten + 6 ones + 7 hundreds + 5 tens + 3 ones
- 6. The football team scored 4 touchdowns, worth 6 points each; kicked 3 extra points, worth 1 point each; and kicked 1 field goal, worth 3 points. What was the team’s final score? Express the relationship using English sentences, then use that sentence to write the situation in math language (an expression or an equation). T = 4 • 6 + 3 • 1 + 1 • 3 Football Score Total Score is 4 touchdowns + 3 extra points + 1 field goal
- 7. Car Price $21,000 Sales Tax is 6% Dealer Rebate is $1,000 In the end, how much will you pay for your new car? New Car
- 8. Christmas Shopping There’s a 20% off sale on fashion accessories. You buy your mom a necklace regularly priced at $14 and a belt marked $23. You have a coupon for 10% off your purchase.
- 9. Back to School Shopping You buy your son a pair of pants for $15 and five uniform shirts that are $12 each. You have a coupon for $5 off pants. Express the relationship using English sentences, then use that sentence to write the situation in math language (an expression or an equation).
- 10. Basketball Score Marquis’ team made 11 successful free throws (1 point each), 25 two-point shots, and 8 three-point shots. Express the relationship using English sentences, then use that sentence to write the situation in math language (an expression or an equation).
- 11. Movie Night Tickets : $8 Children 12 and under $10 Adults You take 4 children and 2 adults to a movie and splurge for a large popcorn.
- 12. Multiply and then Add 46 x 35 230 +1380 1610
- 13. We need to add and subtract LIKE items a. 3 + 7 • 5 b. How much money would Luz have if she had 3 pennies and 7 nickels? 2 thousands + 4 hundreds + 1 ten + 6 ones + 7 hundreds + 5 tens + 2 ones
- 14. Video One is one … or is it?
- 15. How Much Money Do You Have? You have three $20 bills, two $5 bills, eight $1 bills, and seven quarters. How much money do you have? Express the relationship using an informal sentence; then use that sentence as the framework for writing a mathematical equation of the problem. Explain and justify the computation step by step.
- 16. Why are multiplication and division done before addition and subtraction?
- 17. When do we simplify the exponent?
Hinweis der Redaktion
- “How would you read this problem?”“What answer do you think the answer is?” (50 or 38)“Instead of reading ‘3 plus 7 times 5,’ what if we read ‘3 plus (or ‘added to’ or ‘combined with’) 7 sets of 5’?” Does that change your answer?”(click)“Now what answer do you think the answer is?” (38) “Why?” listen to participants’ responses “How did you know to convert the nickel into cents? How did you know how to do the multiplication, before the addition?” (unit conversion)“Using context is one way that we can arrive at a reasonable answer. It’s easier to understand than ‘naked numbers’.” “So, did you have to do addition or multiplication first?”
- “This is the essential question we will explore today.”
- “How can we turn this into a true equation? 2 what-cha-ma-call-its added to 8 something-or-others makes 28 whose-a-majigs”Allow time for students to think of an idea before clicking to the next screen.
- “We make the assumption that each numeral without context represents the quantity of ones.”Another idea: 2 dimes and 8 pennies = 28 cents
- “How would you go about adding 2,416 and 753?” (pause for answer)(click) Reword depending on answer – “Why do many of us rewrite the problem vertically?” “Why are you lining it up? Why do the 4 and the 7 have to be added together?” The 4 is actually 400 and the 7 is actually 700. “We have to add ones with ones, tens with tens, etc. We must add like things.” (1.NBT.4 – hundreds) (2.NBT.7 – thousands)(click) to show place value view
- Insist on writing in English sentences first! This is not about finding the correct answer; it’s about building a foundation for algebra through understanding and writing expressions.The total score is made up of four touchdowns which are six points each, three extra points worth one point each, and one field goal worth three points.The touchdown and the field goal had to be converted to points (like items) before the subtotals could be combined for the final score.
- Use 10% for most classes to figure tax. Eliminating the messy numbers allows them to get past the calculation, and focus on whether or not the order matters.Tax first…21,000 x .06 = 1,260 tax1,260 + 21,000 = 22,26022,260 – 1000 = 21,260 total cost of carRebate first…21,000 – 1,000 = 20,00020,000 x .06 = 1,200 taxTotal cost of the car 21,200“Does order matter in this situation?”
- More complicated question. Determine if this example appropriate for the group.
- 15 – 5 + 5(12)“Does the order matter in this situation?”
- 11(1) + 25(2) + 8(3)
- “The context here is Movie Night. What story can you give this to create a series of operations? (click for example if needed) Write up a situation in English sentences, and then write it in math language.”Share English sentences and ask other students to give a math sentence.Student sample: 4 children at $8 each and 4 adults at $10 each and drinks are $2 per person; 4(8) + 4(10) + 2(8)“The number 8 in the expression means two different things. What does it mean to multiply a person and a dollar value?” “What is our unit?” Dollars per person. “Can we add a person to a dollar?” No, we are converting everything to dollars.
- In our traditional algorithm, multiplication comes before addition. (4.NBT.5 – two-digit by two-digit multiplication)
- This link is for YouTube because for me it has been more reliable. If you’d like to you can go to directly to Ted Ed.http://ed.ted.com/lessons/one-is-one-or-is-it There are a few questions to go with the video there.
- “What was the conversion made here?” Could have been to dollars using decimals, quarters, or cents.My solution:The amount of money I have is made up of three twenty-dollar bills, two five-dollar bills, eight one-dollar bills, and seven quarters.My Money = 3 20s + 2 5s + 8 1s + 7 quarters.$ = 3 • 20 + 2 • 5 + 8 • 1 + 7 • .25$ = 60 + 10 + 8 + 1.75I have $79.75
- This was our essential question today. On your paper, put into words an explanation to the question: “Why are multiplication and division done before addition and subtraction?”Multiplication and division are done before addition and subtraction in order to convert groups of items into subtotals of like items that can be combined for the total.
- “What about exponents? When should we simplify the exponent in an expression? Why?”Ask probing questions to get at – exponents are essentially multiplication and therefore done with the multiplication.(6.EE.1 – write and evaluate expressions with exponents)[answer to exponent example expression is 37]