Multiplying Fractions

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Objective

SWBAT apply properties of operations to the multiplication of fractions.

Big Idea

Using multiplication of rational numbers to solve problems involving accumulating resources measured in fractional quantities.

Launch

10 minutes

Students will complete a pre-assessment to show what they know and remember how to multiply fractions. Students will not use a calculator. I want to see what they know about the multiplication algorithm.

Explore

25 minutes

I will set up a discussion of the Vacation Function worksheet by telling the students that I earn vacation days each month. To take time off from work, I have to accumulate the time or I will not get paid. The task will be to find the number of days I have acquired at the end of the school year. At this point in the lesson, I am more interested in the process students will use to determine the number of days (MP1, MP2, MP4). By asking how to explain their thinking, I can learn more about what my kids currently understand then if I just ask for the answer.

If a student volunteers that we should multiply, I will ask if there are other ways. I want them to recognize that repeated addition, if offered, could be a long way to approach the problem. Multiplication will be faster and results in the same answer.

Supplemental Resource: There is a Discovery Education video that walks students through calculating the number of vacation days earned by an employee that can be used in addition to the Vacation Function worksheet.

Create link to: http://app.discoveryeducation.com/search?Ntt=sandwich

After we finish the Vacation Function sheet, we will move to the partner worksheet, Multiplying Fractions. As pairs work on solving the problems, I can visit groups and check for understanding and provide support when needed. When the partners finish the problems, we can either have a volunteer come to the interactive whiteboard or document camera to show how to solve each problem. Or, pairs can trade papers to review the work of another group. As they are looking at someone else’s paper, I want partners to notice what steps were taken to solve the problem. Looking at the different complexities in the problems, I can make decisions about grouping for other activities in the unit. I can also decide about necessary differentiation to support students.

I anticipate that some students will have difficulty solving problems with mixed numbers. I can work with pairs to intervene and help students. If students cannot solve those problems, we can reteach activities from adding fractions and extend them to multiplication. Students who demonstrate understanding of the different problems can participate in an extension of these kinds of problems or move into division using fractions.

 

 

Summary

5 minutes

Wrap Up:  To wrap up the lesson, I will ask students to solve a problem multiplying fractions on an Exit Ticket. The question will be similar to the questions on the pre-assessment to determine if any understanding was supported through the activity with the video. To support their answer, students can draw a model of their work or write a description of their work. This exit ticket will also provide some insight as to how to approach the next day’s lesson. Is the distinction so great between what my students know that I need to do an extension activity for some students and an intervention lesson for others? Or do we need an intervention for the whole class?

 

Exit Ticket Problem:

If Cassie earns ______ vacation days each month, how many vacation days will she have earned after working for the company for ______ months?