Estimating with Percents

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Objective

SWBAT estimate the percent of a number

Big Idea

Is there a difference between estimating a percent and finding a percent of a number?

Launch

5 minutes
  • POD

As students enter the room, they will have a seat, take out their Problem of the Day (POD) sheet and begin to work on the question on the SMARTboard. The POD allows students to use MP 3 continually based on the discussions we have about the problem each day.

The POD focuses student thinking on converting percents, fractions, and decimals into other forms. As we begin to estimate percents, I don’t want students to get caught unable to estimate because the conversion is a problem for them.

How do you change these percents to fractions and decimals: 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%.

What are the decimal equivalents?

How can you use 10% to find the fraction and decimal equivalents for the list of percents.

Sometimes an exact answer is not needed when using percents. Name a situation when an exact answer may not be necessary.

Explore

30 minutes

To explore estimates we will do examples together that students can add to their notes. We will work through the examples as a whole class so that students can see how the problems are being solved and possibly see some alternate ways to solve the problem.  After we work through the problems using estimation, we can go back through them finding exact answers. My goal is to have them see the effectiveness of a reasonable estimate along with how close the estimate is to the exact answer. We can then discuss the relevance of using one form over the other.

Landing

5 minutes

To end class, I want the exit ticket to help students make the connection between the last two activities we have done in class. The question will serve as a formative assessment to determine who understands the relationship between estimating percents and finding percents of numbers. Do they recognize the similarities of each process?

EXIT TICKET

How could you round 62%?

What is 60% written as a fraction?

How could you use this to estimate 62% of 500?