It is important to think about ways to conserve, or save, water. A little water here, a little water there—it might not seem like you use that much water during the day. But have you ever measured the amount of water you use when you brush your teeth or take a shower? It might be more than you think.

Some people estimate that you use 4 quarts of water every time you brush your teeth if you leave the faucet running. That means that if you brush your teeth twice a day, you are using 8 quarts a day, which is 2,920 quarts a year!

It's hard to understand how much 2,920 quarts is. Sometimes, converting, or changing, a measurement into another unit helps you understand how large that amount truly is. In this lesson, you will learn how to convert different units of measurement.

Goals
Here are the big ideas you will learn about in this lesson:

• Measurements can be converted from one unit to another.
• Unit conversions can be represented as ratios.

Strategies
You will be using many reading and writing strategies to complete this lesson. The key strategies that you will focus on are:

• Making inferences
• Determining important information
• Constructing summaries

• equivalent
• ratio
• unit of measurement

Think about the amount of water you use when you take a shower. Do you think you use 10 gallons, 100 gallons, or somewhere in between?

You can do a simple experiment to find out. Click “View” on the left to watch Noreen as she discovers how much water she uses in an average shower. After watching, keep reading below and answer the question.

Rather than running the shower for 10 minutes and measuring all of that water, Noreen measures how much water comes out of the shower in half a minute. She knows that there are two half minutes in one minute, so she multiplies by 2 to calculate how much water she used in 1 minute. Finally, because she wants to know how much water she used in 10 minutes, she multiplies by 10.

If Noreen had let the water run for 2 minutes instead of half a minute, do you think she would still find that she used 320 cups of water during her 10-minute shower? Think about the math calculations she would have to do in that situation. Explain your answer in two to three sentences.

Noreen wants to know whether she used more or less than 25 gallons of water. How can she compare 320 cups to 25 gallons?

One way is to convert 320 cups into an equivalent number of gallons.

Doing a unit conversion does not change the amount of water that she used. It just allows her to measure the water using another unit of measurement: gallons instead of cups.

Click "View" on the left to see Noreen convert 320 cups into gallons. After watching, keep reading below and answer the question.

Sixteen (16) cups is equivalent to one (1) gallon. Noreen divides 320 ÷ 16 and calculates that this is equal to 20 gallons. A gallon is larger than a cup, so it makes sense that 20 gallons is equivalent to 320 cups.

Since 20 gallons is less than 25, Noreen's water usage is below average.

Now think about this: Dustin did the same experiment and found that he used 240 cups of water in the shower. In one to two sentences, explain how he can figure out how many gallons this is equivalent to. Include the word "convert" in your answer.

Another way you can do unit conversions is to use ratios.

Here’s how it works. The relationship "16 cups is equivalent to 1 gallon" can be written as the ratio 16 cups : 1 gallon. And since the quantities are equal, you can write the ratio either way—cups to gallons, or gallons to cups, as shown to the left.

Now, if you want to convert 320 cups to gallons, then you write the ratio as a fraction. Write the number of gallons on top (the numerator) and cups on the bottom (the denominator). You will see why in a moment! Then multiply:

You can cross out the "cups" measurement because it appears in the numerator and denominator. Notice that once you do that, you are left with gallons—the unit you were looking for!

Remember that 320 gallons/16 is the same as 320 gallons ÷ 16, or 20 gallons. You end up dividing, just as Noreen did in the video.

Doing a unit conversion is all about finding the right ratio. Here are some common ratios that you have probably seen:

Each of these ratios contains equivalent measurements: 1 foot is the same as 12 inches, for example, and 60 minutes is the same as 1 hour.

To convert a measurement, you need to figure out the units you have and the units you want. Then it is just a matter of setting up a multiplication problem. Here are two examples:

How many hours is 4 days?

How many miles is 15,840 feet?

Now you try it: 96 inches is equivalent to how many feet? In one to two sentences, explain the math you used to solve this problem and provide your answer.

How much water do you use around the house every day? It might be more than you think. Now that you know how to do unit conversions, you can figure out how much water various activities use and how you can conserve water.

Click "View" on the left to read the passage and then answer the question below.

What are some steps you can take to conserve water at home? In your answer, talk about the changes you could make and the importance of conserving water. Write your answer in two to three sentences.

The videos you have seen and the text you have read have helped you learn how to convert units of measurement.

Now show what you have learned so far by answering these three questions. Be sure to save all your answers before you go to the next screen.

You will now check your understanding of the vocabulary words for this lesson by placing them in sentences. Click "View" on the left to begin the activity.

Before moving to the next screen, choose two words from the vocabulary list and write a new sentence for each word.

Vocabulary words: calculate, conserve, convert, equivalent, ratio, unit of measurement

Have cups, need gallons? Knowing a few ratios can help you find the units of measurement that you need.

In this activity, you will set up and solve some unit conversions.

Click "View" on the left to begin the activity. Your teacher will review the answers with you.

Then, before moving on to the final assignment, you may want to watch this lesson's videos again or reread the passage.

Shower Estimation

Video: 1m 27s

View

Unit Conversion

Video: 0m 39s

View

Conserving Water at Home

Document

View

In this lesson, you have learned how to convert units of measurement. You have also thought about some of the reasons why conserving water is important. You will now write an essay that shares what you have learned and what you think about it.

Begin by reviewing your notes. Click "review my work" above and view or print out the screen that pops up.

Final Assignment Instructions

• Click Unit Converstion: Water Use—Final Assignment (PDF).
• Choose one of the topics in the PDF and write an essay.
• Organize your response so that it includes at least three supporting details that you have learned from the reading passage, video(s), and other materials in this lesson.
• Use at least three vocabulary words (or a form of the words) as part of your supporting details. For example, for the word jump, you could use jumps, jumped, or jumping.