standard_description: Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases:
- The numbers from 11 to 19 are composed of a ten and one, two, three, four, five, six, seven, eight, or nine ones.
- The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and 0 ones).
- 10 can be thought of as a bundle of ten ones — called a “ten.”
problem_activity: Activity
The goal of this activity is for students to be reminded of the importance of measures of variability. Students compare data sets and decide which is the better option. Students must explain their reasoning for choosing one of the options and use statistics to justify their answers. This activity helps students gain more practice working with using variability to compare data sets.
Launch
Allow students to work individually or in pairs.
Student Facing
Choose the best option based on the given data. Use a measure of center and measure of variability to justify your answers.
Participants’ ages at camp A
[IMG]
Participants’ ages at camp B
mean: 11.93 years, mean absolute deviation: 1.65 years
Servers’ tip amounts at restaurant A
mean:
$
15, mean absolute deviation:
$
1.5
Servers’ tip amounts at restaurant B
[IMG]
​​​​​​Which camp would you prefer to work for? Explain your reasoning.
Which camp would you prefer to attend? Explain your reasoning.
At which restaurant would you want to be a server? Explain your reasoning.
Student Response
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Activity Synthesis
Discuss how students made their decisions. Here are sample questions to promote class discussion:
“How did the variability influence your choices?" (When there is greater variability, the values are more spread out, so that helped me think about whether I wanted consistent values or a wider range.)
"What are some situations in which less variability might be preferred?" (When you want the results to be consistent and reliable. Examples include the number of points scored by a good player, the miles a car can go on a single gallon of gas, or the price of milk.)
“How would the process of choosing the best situation be different if you were given a box plot?” (With a histogram or box plot, I wouldn’t have known exact numbers, so I would probably have to use a measure like IQR or the median to help make my decision.)


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