Day 52: Why 4 and 1/3 Times 2/5 Isn't 4 and 2/15

6th Grade Math Standards: 6.NS.1 Interpret and compute quotients of fractions, and solve word problems involving division of fractions by fractions, e.g., by using visual fraction models and equations to represent the problem. For example, create a story context for (2/3) ÷ (3/4) and use a visual fraction model to show the quotient; use the relationship between multiplication and division to explain that (2/3) ÷ (3/4) = 8/9 because 3/4 of 8/9 is 2/3. (In general, (a/b) ÷ (c/d) = ad/bc .) How much chocolate will each person get if 3 people share 1/2 lb of chocolate equally? How many 3/4-cup servings are in 2/3 of a cup of yogurt? How wide is a rectangular strip of land with length 3/4 mi and area 1/2 square mi?

Objective: Analyze the products of fraction problems in a mathematical context; find products in a real world context through multiplying fractions or using equivalent ratios

Agenda:

1. Which one doesn't belong?
2. QSSQ 
3. Review the homework
4. Exit Ticket on why 4 and 1/3 times 2/5 does not equal 4 and 2/15
5. Mashed Potato Recipes from Yummy Math

Assessment: The homework was assessed to see students comfort level in cross reducing. Some students were on the fence as to how cross reducing would make life simpler and not more complicated. There was the exit ticket (the subject of the amount of liquid in the glass) and the mashed potato recipes were collected by me to see where students were on old concepts integrated with new concepts.

Glass Half-Full: About 83% of the students had something logical to say about the exit ticket. I think it helped that it was connected to the question of the day as well.

Regrets: The mashed potato exercise was good, but there was no time to review the results. I even gave them the answer to problem one. Somehow we have to do a better job of time management because it would have been good to review for the whole crew after collecting the work and seeing the various misconceptions and multiple points of entry for those that did solve.

 Here the student triples the ingredients when the number of people to serve was not tripled.

Here the student correctly changes the ingredient, but the denominators in each picture are different.

Link: Many of the ideas in this blog post about 16 Ideas for Student Projects Using Google Docs, Slides, and Forms I was familiar with, but I thought a cool add on for my curriculum was to have students create their own form and have classmates answer it when we do statistical questions.