Presentation on theme: "National Council of Teachers of Mathematics"— Presentation transcript:
1National Council of Teachers of Mathematics Moving from Additive to Multiplicative Thinking: The Road to Proportional ReasoningNational Council of Teachers of MathematicsApril 15, 2011Melissa Hedges, MathematicsTeaching Specialist, MTSDBeth Schefelker, Mathematics Teaching Specialist, MPSConnie Laughlin, Mathematics Instructor, UW-MilwaukeeThe Milwaukee Mathematics Partnership (MMP), an initiative of the Milwaukee Partnership Academy (MPA), is supported with funding by the National Science Foundation.
2Root Beer or Cola?During dinner at a local restaurant, the five people sitting at Table A and the ten people sitting at Table B ordered the drinks shown below. Later, the waitress was heard referring to one of the groups as the “root beer drinkers.” To which table was she referring?Table ATable B
3Sharing Your Thinking Share your answer and thinking with a neighbor. How are your thoughts alike and how are they different?
4Two Perspectives on Thinking Absolute Thinking (additive)Comparing the actual number of root beer bottles from Table A to Table B.How might an additive thinker answer which is the root beer table?How might they justify their reasoning?Relative (multiplicative)Comparing amount of root beers to the total amount of beverages for each table.How might a relative thinker respond to this task?Table ATable B
5Learning Intention and Success Criteria We are learning to… develop an awareness of proportional situations in every day life.By the end of the session you will be able to…recognize the difference between additive thinking (absolute) and multiplicative thinking (relative) in student work.
6Which family has more girls? The Jones Family (GBGBB)The King Family (GBBG)
7Thinking about “more” from an absolute and relative perspective After you’ve read turn and talk:How would an additive thinker interpret “more” in this context?How would a relative thinker interpret “more” in this context?In what way will questioning strategies surfacing relative thinking?
8Surfacing relative (multiplicative) thinking… Keeping the relative amount of boys to girls the same, what would happen if…The Jones Family grew to 50?The King family grew to 40?
9What happens when… Keeping the ratios of boys to girls the same…. The Jones Family grew to 100?The King family grew to 100?
10Which is a better deal?M&M’s were featured in the weekly advertisement from two different stores.Greenwall’s Drug:2 – 16 oz packages of M & M’s $ 3.00.Drekmeier Pharmacy:3 – 16 oz packages of M & M’s $ 4.00.Which store offered a better deal?
11Proportional Reasoning Proportional reasoning has been referred to as the capstone of the elementary curriculum and the cornerstone of algebra and beyond.It begins with the ability to understand multiplicative relationships, distinguishing them from relationships that are additive.Van de Walle,J. (2009). Elementary and middle school teaching developmentally. Boston, MA: Pearson Education.11
12Proportional Reasoning vs Proportions Proportional reasoning goes well beyond the notion of setting up a proportion to solve a problem—it is a way of reasoning about multiplicative situations.In fact, proportional reasoning, like equivalence is considered a unifying theme in mathematics.
13What is a ratio?An ordered pair of numbers that express a multiplicative (relative) comparison.Types of ratiosPart-to-Part: number of girls to number of boysPart-to-Whole: number of girls to number ofchildren in the family
14What is a proportion?A proportion is a statement of equality between two ratios.Jones Family 2:5 = 20:50 = 40:100King Family 2:4 = 20:40 = 50:100What do these proportions represent?Question raises ideas about part-whole, part-part relationships. If need be you could explore the proportional relationships for the Jone family.
15Big Ideas of Fractions as Ratios A ratio is a multiplicative comparison of quantities.Different types of comparisons can be represented as ratios.Ratios give the relative sizes of the quantities being compared, not necessarily the actual sizes.
16CCSS Grade 6 – Narrative Ratios and Proportional Relationships 1. Students use reasoning about multiplication and division to solve ratio and rate problems about quantities. By viewing equivalent ratios and rates as deriving from, and extending, pairs of rows (or columns) in the multiplication table, and by analyzing simple drawings that indicate the relative size of quantities, students connect their understanding of multiplication and division with ratios and rates. Thus students expand the scope of problems for which they can use multiplication and division to solve problems, and they connect ratios and fractions. Students solve a wide variety of problems involving ratios and rates.
17MPS Students Benchmark 3 – Grade 7 CR Item From a shipment of 500 batteries, a sample of 25 was selected at random and tested. If 2 batteries in the sample were found to be defective, how many defective batteries would be expected in the entire shipment?
19Ratio and Proportion What’s the difference? Ratio and proportion do not develop in isolation. They are part of an individual’s multiplicative conceptual field, which includes other concepts such as multiplication, division, and rational numbers.Lo, J., & Watanabe, T. (1997). Developing ratio and proportional schemes: A story of a fifth grader. Journal for Research in Mathematics Education, 28,
20Proportional Reasoning Proportional reasoning has been referred to as the capstone of the elementary curriculum and the cornerstone of algebra and beyond.It begins with the ability to understand multiplicative relationships, distinguishing them from relationships that are additive.Van de Walle,J. (2009). Elementary and middle school teaching developmentally. Boston, MA: Pearson Education.
21Thank You for coming! Melissa Hedges email@example.com Connie LaughlinBeth Schefelker