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# Using a Ratio Table

Lesson 2 of 7

## Objective: SWBAT use ratio tables to solve a variety of problems.

*85 minutes*

#### Do Now

*10 min*

The students will be using a variety of mental math strategies in completing this set of questions. These problems can help assess students’ mental computation abilities. The problems should be done as a class and read aloud so that students solve them mentally and can discuss their strategies. When observing student strategies, you should expect to see them devising shortcuts to help them add/subtract numbers mentally. As an extension, the students can explain their strategy for each problem. ** (SMP 2 and 6)**

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The students will be identifying two ways to solve a problem. Strategies may include skip counting, multiplying or dividing. The object here is to get students to understand that there are multiple ways to solve one problem. **(SMP 1 and 3)**

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In this section, students will be looking at ratio tables to decide what steps were taken to get to the answer. The students will be using adding, times 10, doubling, halving, subtracting and multiplying as some of their strategies. Each slide shows the intermediate steps that were used. Then, allow the students time to look at 2 problems to discover the steps used to solve it. **(SMP 4)**

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#### Ratio Table Show Down

*30 min*

The students will be working in groups and using ratio tables to solve problems using a Showdown. Each student will work on the problem independently and then show their tablemates their strategies. Students should be allowed to explain their strategy while others in the group listen and then critique as needed.**(SMP #3) **When all students have been given the opportunity to explain their strategy, call a random student from each group to show their answer and explain.

Students may struggle with coming up with the initial ratio. If this happens, have the students tell you what they know about the problem. For example, if roses are sold in boxes of 15, what does that tell us about our ratio? How many numbers do we need to begin with? If I have 1 box, how many roses to do I have? **(SMP1 and 2)**

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#### Closure

*15 min*

I want to know if students really understand how to use a ratio table. I’m going to have them create their own examples for each of the following approaches:

Adding

Doubling

Subtracting

Times 10

Halving

Multiplying

If time permits, I’m going to have them come up with other approaches to use when filling in a new column. (x3,x4,x5 etc). I would like them to say that the approach you use will depend on what you are trying to find. If you know your multiplication facts then it would be good to use multiplication. If you are not so good at them, then easier multiplication or addition would be best.

#### Resources

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Thank you. I loved your power point on using ratio tables, and was able to utilize it for a full 90 minute block. The students gleaned a lot from it and now know how to use tables smartly.

Rosemarie Pereira

Paterson, NJ

| 2 years ago | Reply

Hi Wendy,

Thank you for the feedback. I really enjoyed teaching ratios using the ratio table. The best advice I have to offer is allow your students some time to develop this skill. I introduced the strategies first (multiplying, dividing, times 10, adding, and subtracting). The biggest struggle is when they have to add or subtract columns together. They want to add numbers to columns when they really need two columns to add together to maintain the ratio. My kids use ratio table a lot, so I hope this works for you as well.

| 3 years ago | Reply

Hi Michelle,

I'm getting ready to teach ratios using the ratio table and was wondering what was the best way to go about doing so. This lesson offers everything I need to get into the lesson and your examples are great for my students since I teach special needs kids. Thank you for such a great lesson, as I said before, it offers everything I need.

Wendy M.

| 3 years ago | Reply*expand comments*

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