7th Grade Math · Unit 1
Choose a line plot, a stem-and-leaf plot, a circle graph, or a histogram.
Line plot
A line plot shows every value. It works well when the data set is small.
You can see each number and which number appears most often.
Stem-and-leaf plot
A stem-and-leaf plot keeps the actual numbers and shows the shape.
The stem is the front of the number. The leaf is the last digit.
Circle graph
A circle graph shows parts of a whole. Use it for categories.
Favorite color, favorite lunch, and way of getting to school are categories.
Histogram
A histogram groups numerical data into intervals. The bars touch, and the height is the count.
It shows the shape and hides the exact values. A list of 40 scores grouped by tens fits a histogram. Favorite color does not.
Name the display, or match it to the phrase.
18 students named a favorite color.
What kind of display is this?
It shows parts of a whole for categories.
Circle graph.
Answer: Circle graph.
Fifteen homes reported how many pets they have. Each number is from 0 to 4.
What kind of display is this?
It shows every numeric value in a small set.
Line plot.
Answer: Line plot.
Ten students listed how many pages they read: 12, 15, 18, 20, 23, 24, 27, 31, 33, and 36.
| Stem | Leaves | |
|---|---|---|
| 1 | | | 2 5 8 |
| 2 | | | 0 3 4 7 |
| 3 | | | 1 3 6 |
A stem of 1 and a leaf of 2 means 12. Stem 1 leaves 2 5 8. Stem 2 leaves 0 3 4 7. Stem 3 leaves 1 3 6.
What kind of display is this?
It keeps the actual numbers and shows the shape.
Stem-and-leaf plot.
Answer: Stem-and-leaf plot.
Ten bus rides were grouped by intervals of minutes.
What kind of display is this?
The bars touch, and each height is a count for an interval.
Histogram.
Answer: Histogram.
23 students named a favorite lunch.
Which phrase matches this display: parts of a whole, or every numeric value in a small set?
Favorite lunch is a category, and the slices are parts of the whole group.
Parts of a whole. This is a circle graph.
Answer: Parts of a whole. This is a circle graph.
Fourteen students listed books read. The values are small whole numbers from 0 to 6.
Which phrase matches this display: parts of a whole, or every numeric value in a small set?
Each mark is one value, so nothing is hidden in an interval.
Every numeric value in a small set. This is a line plot.
Answer: Every numeric value in a small set. This is a line plot.
Nine noon temperatures were recorded: 61, 63, 67, 68, 70, 72, 74, 75, and 78.
| Stem | Leaves | |
|---|---|---|
| 6 | | | 1 3 7 8 |
| 7 | | | 0 2 4 5 8 |
A stem of 6 and a leaf of 1 means 61. Stem 6 leaves 1 3 7 8. Stem 7 leaves 0 2 4 5 8.
What kind of display is this?
You can read each temperature from the stem and the leaf.
Stem-and-leaf plot.
Answer: Stem-and-leaf plot.
Ten plant heights were grouped into touching intervals.
What kind of display is this?
Numerical heights are grouped, and the exact heights are hidden.
Histogram.
Answer: Histogram.
28 students named how they get to school.
What kind of display shows these parts of a whole?
Bus, walk, car, and bike are categories.
Circle graph.
Answer: Circle graph.
Fourteen bus waits, in minutes, are each from 0 to 5.
What kind of display shows every numeric value in this small set?
The set is small, and every wait is marked.
Line plot.
Answer: Line plot.
Eight quiz scores are 78, 81, 83, 85, 86, 88, 90, and 92.
| Stem | Leaves | |
|---|---|---|
| 7 | | | 8 |
| 8 | | | 1 3 5 6 8 |
| 9 | | | 0 2 |
A stem of 7 and a leaf of 8 means 78. Stem 7 leaves 8. Stem 8 leaves 1 3 5 6 8. Stem 9 leaves 0 2.
What kind of display is this?
The actual scores are still listed, and the shape shows by tens.
Stem-and-leaf plot.
Answer: Stem-and-leaf plot.
Choose one of the two displays, and explain in one or two lines.
The lunch graph shows 23 students.
You want parts of a whole for favorite lunch. Should you use a circle graph or a histogram?
A histogram cannot use favorite lunch as an interval.
Circle graph. Favorite lunch is a category, and a histogram needs numbers.
Answer: Circle graph. Favorite lunch is a category, and a histogram needs numbers.
Eight quiz scores out of 10 are 6, 7, 7, 8, 8, 8, 9, and 10.
You want every score. Should you use a line plot or a histogram?
Eight values on a short number line are easy to mark one by one.
Line plot. The set is small, and a histogram would hide the exact scores.
Answer: Line plot. The set is small, and a histogram would hide the exact scores.
There are 40 quiz scores, and you want the shape in groups of ten.
Should you use a histogram or a line plot?
The histogram hides each exact score, which fits this goal.
Histogram. A line plot of 40 scores is crowded, so the shape by tens is harder to see.
Answer: Histogram. A line plot of 40 scores is crowded, so the shape by tens is harder to see.
The page counts are 12, 15, 18, 20, 23, 24, 27, 31, 33, and 36.
| Stem | Leaves | |
|---|---|---|
| 1 | | | 2 5 8 |
| 2 | | | 0 3 4 7 |
| 3 | | | 1 3 6 |
A stem of 1 and a leaf of 2 means 12. Stem 1 leaves 2 5 8. Stem 2 leaves 0 3 4 7. Stem 3 leaves 1 3 6.
You want to keep the actual page counts. Should you use a stem-and-leaf plot or a circle graph?
The stem-and-leaf plot keeps every number and shows the shape.
Stem-and-leaf plot. A circle graph is for categories, not a list of page counts.
Answer: Stem-and-leaf plot. A circle graph is for categories, not a list of page counts.
28 students get to school by bus, walking, car, or bike.
Should you use a circle graph or a line plot?
Bus and walk are not positions on a number line.
Circle graph. These are categories and parts of a whole. A line plot needs numbers.
Answer: Circle graph. These are categories and parts of a whole. A line plot needs numbers.
Ten plant heights are grouped to show the shape.
Should you use a histogram or a circle graph?
A circle graph is for categories. It is not the display for this number line.
Histogram. Heights are numbers, and you want the interval shape.
Answer: Histogram. Heights are numbers, and you want the interval shape.
Fifteen homes have 0, 1, 2, 3, or 4 pets.
Should you use this line plot or a histogram?
A line plot is a good fit for a small numerical set.
Line plot. The set is small, and every value shows. A histogram would hide the exact counts.
Answer: Line plot. The set is small, and every value shows. A histogram would hide the exact counts.
Eight quiz scores are 64, 70, 73, 75, 78, 82, 84, and 91.
| Stem | Leaves | |
|---|---|---|
| 6 | | | 4 |
| 7 | | | 0 3 5 8 |
| 8 | | | 2 4 |
| 9 | | | 1 |
Stem-and-leaf plot. A stem of 6 and a leaf of 4 means 64. Stem 6 leaves 4. Stem 7 leaves 0 3 5 8. Stem 8 leaves 2 4. Stem 9 leaves 1.
You need each exact score. Should you use a stem-and-leaf plot or a histogram?
The stem-and-leaf plot keeps the actual numbers and still shows the shape.
Stem-and-leaf plot. A histogram would hide the exact scores inside an interval.
Answer: Stem-and-leaf plot. A histogram would hide the exact scores inside an interval.
24 students named a favorite music type.
Should you use a circle graph or a histogram?
Favorite music is like favorite color. It is parts of a whole.
Circle graph. Music type is a category, not a number for a histogram.
Answer: Circle graph. Music type is a category, not a number for a histogram.
Fourteen waits are marked in minutes from 0 to 5.
Should you use a line plot or a circle graph?
A circle graph is for categories, not for every small numeric value.
Line plot. The minutes are numeric values. A circle graph would drop the order of the number line.
Answer: Line plot. The minutes are numeric values. A circle graph would drop the order of the number line.
Forty bus times are grouped by 10 minutes.
You want that grouped shape. Should you use a histogram or a stem-and-leaf plot?
Use the histogram for the interval shape. You do lose the exact times.
Histogram. It matches groups of 10. A stem-and-leaf plot would keep each time, but that is not the grouped picture you want.
Answer: Histogram. It matches groups of 10. A stem-and-leaf plot would keep each time, but that is not the grouped picture you want.
Pick the display. Say what a worse choice would lose.
18 students named a favorite color: blue, green, red, or purple.
Which display fits, and what would a histogram lose?
A circle graph keeps the parts of the whole.
Use a circle graph. Favorite colors are not a histogram. A histogram would lose the categories, because color is not a number.
Answer: Use a circle graph. Favorite colors are not a histogram. A histogram would lose the categories, because color is not a number.
Eight quiz scores are 78, 81, 83, 85, 86, 88, 90, and 92.
| Stem | Leaves | |
|---|---|---|
| 7 | | | 8 |
| 8 | | | 1 3 5 6 8 |
| 9 | | | 0 2 |
A stem of 7 and a leaf of 8 means 78. Stem 7 leaves 8. Stem 8 leaves 1 3 5 6 8. Stem 9 leaves 0 2.
Which displays can keep every score, and what would a histogram lose?
Eight scores are a small set, so you do not have to group them.
A line plot or a stem-and-leaf plot can keep every score. A histogram would lose the exact scores inside each interval.
Answer: A line plot or a stem-and-leaf plot can keep every score. A histogram would lose the exact scores inside each interval.
You have 40 quiz scores and you want the shape in groups of ten.
Which display fits, and what would a line plot lose?
A list of 40 scores grouped by tens is a histogram.
Use a histogram. A line plot of 40 scores would lose a clear shape. The histogram hides each exact score, which fits groups of ten.
Answer: Use a histogram. A line plot of 40 scores would lose a clear shape. The histogram hides each exact score, which fits groups of ten.
Ten song lengths in seconds are 121, 128, 134, 135, 140, 147, 152, 156, 163, and 171. You want the actual numbers and the shape.
| Stem | Leaves | |
|---|---|---|
| 12 | | | 1 8 |
| 13 | | | 4 5 |
| 14 | | | 0 7 |
| 15 | | | 2 6 |
| 16 | | | 3 |
| 17 | | | 1 |
Stem-and-leaf plot. A stem of 12 and a leaf of 1 means 121. Stem 12 leaves 1 8. Stem 13 leaves 4 5. Stem 14 leaves 0 7. Stem 15 leaves 2 6. Stem 16 leaves 3. Stem 17 leaves 1.
Which display fits, and what would a circle graph lose?
The stem keeps each length.
Use a stem-and-leaf plot. A circle graph would lose the numerical order and the actual lengths. A histogram would lose the exact lengths.
Answer: Use a stem-and-leaf plot. A circle graph would lose the numerical order and the actual lengths. A histogram would lose the exact lengths.
28 students travel by bus, walking, car, or bike.
Which display fits, and what would a line plot lose?
These are parts of a whole.
Use a circle graph. A line plot would lose the categories, because bus and walk are not positions on a number line.
Answer: Use a circle graph. A line plot would lose the categories, because bus and walk are not positions on a number line.
Fourteen students read 0 to 6 books. You want every value.
Which display fits, and what would a histogram lose?
Every value can show on the line plot.
Use a line plot. The set is small. A histogram would lose the exact number of books inside a wider interval.
Answer: Use a line plot. The set is small. A histogram would lose the exact number of books inside a wider interval.
18 students named a favorite pet: dog, cat, bird, or fish.
Which display fits, and why is a histogram a worse choice?
Do not turn pet names into a numerical histogram.
Use a circle graph. Favorite pet is a category, like favorite color. A histogram would lose the categories.
Answer: Use a circle graph. Favorite pet is a category, like favorite color. A histogram would lose the categories.
Forty bus times are grouped by 10 minutes so you can see the shape.
Which display fits, and what would a line plot lose?
The histogram hides each exact time and shows the groups of 10.
Use a histogram. A line plot of 40 times would lose a clear view of the shape.
Answer: Use a histogram. A line plot of 40 times would lose a clear view of the shape.
Nine temperatures are 61, 63, 67, 68, 70, 72, 74, 75, and 78.
| Stem | Leaves | |
|---|---|---|
| 6 | | | 1 3 7 8 |
| 7 | | | 0 2 4 5 8 |
A stem of 6 and a leaf of 1 means 61. Stem 6 leaves 1 3 7 8. Stem 7 leaves 0 2 4 5 8.
Which display keeps each temperature, and what would one wide histogram bar lose?
The stem-and-leaf plot keeps the numbers and shows the shape.
Use a stem-and-leaf plot. A wide histogram bar could hide the actual temperatures. A circle graph would lose the number line.
Answer: Use a stem-and-leaf plot. A wide histogram bar could hide the actual temperatures. A circle graph would lose the number line.
Fourteen bus waits are a small set of minutes from 0 to 5.
Which display fits, and what would a histogram lose?
The set is small enough for every value.
Use a line plot so every wait shows. A histogram would lose the exact number of minutes.
Answer: Use a line plot so every wait shows. A histogram would lose the exact number of minutes.
Eight more quiz scores are 64, 70, 73, 75, 78, 82, 84, and 91.
| Stem | Leaves | |
|---|---|---|
| 6 | | | 4 |
| 7 | | | 0 3 5 8 |
| 8 | | | 2 4 |
| 9 | | | 1 |
Stem-and-leaf plot. A stem of 6 and a leaf of 4 means 64. Stem 6 leaves 4. Stem 7 leaves 0 3 5 8. Stem 8 leaves 2 4. Stem 9 leaves 1.
A line plot or a stem-and-leaf plot could show them. What would a histogram lose?
With only 8 scores, grouping by tens hides differences you can still list.
Either a line plot or a stem-and-leaf plot keeps every score. A histogram would lose the exact scores inside an interval.
Answer: Either a line plot or a stem-and-leaf plot keeps every score. A histogram would lose the exact scores inside an interval.
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