How to read tables, bar graphs, line graphs and pie charts
TEAS 7 outline: Extract relevant information from tables, charts and graphs
- Read the title, labels, units and scale before any number.
- "How many more" means subtract the two values.
- The steepest segment shows the biggest change, not the lowest or highest point.
- Pie chart percents add to 100%; amount = percent as a decimal × whole.
- If an axis does not start at 0, read the numbers, not the picture.
Key facts
- Read the title, labels, units, scale and key before you read any number.
- In a table, find the row and the column that match the question; "how many more" means subtract.
- Bar graphs compare separate categories; read the top of each bar against the vertical scale.
Show all 6 key factsShow fewer
- On a line graph (time series), time runs along the horizontal axis, and the steepest segment shows the biggest change between neighboring points.
- A pie chart shows parts of one whole, so its percents add to 100%; amount = percent (as a decimal) × whole.
- Each dot on a scatter plot is one item with two measurements; dots rising left to right mean high values go with high values.
Quick check1 question · 2 more at the end
Appointments at a physical therapy clinic during one week
| Day | In-person | Telehealth |
|---|---|---|
| Monday | 32 | 9 |
| Tuesday | 24 | 18 |
| Wednesday | 37 | 6 |
| Thursday | 27 | 12 |
| Friday | 25 | 16 |
According to the table, on which day did the clinic have the fewest in-person appointments?
Correct answer: A.
Use only the In-person column and look for the smallest number: 32, 24, 37, 27, 25. The smallest is 24, on Tuesday. Before answering a table question, check the column heading the question names; the Telehealth column and the daily totals give different answers.
A Correct: Tuesday's 24 is the smallest value in the In-person column.
B Wednesday has the fewest telehealth appointments (6); this reads the wrong column. Wednesday actually has the most in-person appointments.
C Thursday has the fewest total appointments (27 + 12 = 39), but the question asks about in-person appointments only.
D Friday's 25 is close, but Tuesday's 24 is smaller; this comes from not comparing every row.
Full lesson
Each part starts with its main idea. Open a part when you want the details.
The short answer: Before doing any math, read the title, axis labels or column headings, units and scale. Then find the exact row, bar or point the question names and do only the math it asks for. Line graphs show change over time, bar graphs compare categories, pie charts show parts of a whole that add to 100%.
1 What should I check before reading any number?Most chart mistakes happen before any math, so read the frame first. 1 min
Most chart mistakes happen before any math, so read the frame first.
- Title: what is being counted, and for whom?
- Labels and headings: which axis or column answers the question?
- Units: mL, dollars, hours, thousands, percent?
- Scale: what is each gridline worth, and does the axis start at 0?
- Key (legend): which color or bar is which group?
If an axis starts at 50 instead of 0, a bar that looks twice as tall may be only slightly larger. Read the numbers, not the picture.
2 How do I pull the right number from a table?Find the row and column that match the question, then do only the math it asks for. 1 min
Find the row and column that match the question, then do only the math it asks for.
Example 1. A clinic tracked flu shots given.
| Month | Adults | Children |
|---|---|---|
| September | 140 | 85 |
| October | 210 | 120 |
| November | 165 | 95 |
How many more adults than children got flu shots in October?
- Find the row: October.
- Find both columns: adults 210, children 120.
- "How many more" means subtract: 210 − 120 = 90.
Classic wrong turn: adding (330) or sliding into the November row. Put a finger on the row and move straight across.
3 How do I read bar graphs, line graphs and scatter plots?Bar graphs compare categories, while line graphs show one thing changing over time. 1 min
Bar graphs compare categories, while line graphs show one thing changing over time. On a bar graph, read the top of each bar against the vertical scale. If a bar ends between gridlines, estimate how far it sits between them.
On a line graph, time runs along the horizontal axis and the points are joined in order, so trends are easy to spot. The steepest segment is the biggest change between neighboring points.
Example 2. A line graph shows a patient's weight at monthly check-ins: January 182 lb, February 179 lb, March 178 lb, April 172 lb, May 171 lb. Between which two months did weight drop the most?
- Find each change: Jan to Feb −3, Feb to Mar −1, Mar to Apr −6, Apr to May −1.
- Biggest drop: March to April, 6 pounds, the steepest downward segment.
Classic wrong turn: choosing April to May because May is the lowest point. The question asks about change, not the lowest value.
A scatter plot shows two measurements for each person or item as one dot. Read a dot by going straight down to the horizontal axis and straight across to the vertical axis. Dots rising left to right mean high values go with high values, and dots falling mean high values go with low values.
4 How do I read a pie chart?A pie chart shows parts of one whole, so its percents add to 100%. 1 min
A pie chart shows parts of one whole, so its percents add to 100%. To turn a slice into an amount, change the percent to a decimal and multiply by the whole.
Example 3. A family's $2,400 monthly budget is shown as a pie chart: rent 40%, food 15%, transportation 12%, savings 10%, other 23%. How many dollars go to food?
- Check the slices: 40 + 15 + 12 + 10 + 23 = 100. Good.
- Change 15% to a decimal: 0.15.
- Multiply by the whole: 0.15 × 2,400 = $360.
Classic wrong turn: answering $15, or skipping the decimal and getting 15 × 2,400 = 36,000. A slice can never be bigger than the whole.
The one rule to remember: amount = percent (as a decimal) × whole.
Common mistakes
The traps students fall into most. Read these before you practice.
Watch out: "Biggest change" is the steepest segment, not the highest or lowest point.
Watch out: A slice of 15% of $2,400 is 0.15 × 2,400 = $360, not $15 and not 15 × 2,400.
Watch out: If the vertical axis does not start at 0, a bar that looks twice as tall may not be twice as large; read the numbers, not the picture.
Watch out: Use the column the question names (output, not intake; children, not adults); one row off gives a believable wrong answer.
Watch out: "How many more" means subtract the two values, not add them.
How to remember it
Say "frame first, numbers second" every time you meet a chart. Checking the title, labels, units and scale takes seconds and prevents most wrong answers.
Self-check:
- In Example 1, how many flu shots were given in September in total?
- In Example 2, how many pounds did the patient lose from January to May in all?
- In Example 3, how many dollars go to rent, and how much more is that than savings?
Show answers
- 225 flu shots.
- Find the row: September.
- "In total" means add both columns: 140 + 85 = 225.
- 11 pounds.
- January weight minus May weight: 182 − 171 = 11.
- Check by adding the monthly drops: 3 + 1 + 6 + 1 = 11.
- Rent is $960, which is $720 more than savings.
- Rent: 0.40 × 2,400 = $960.
- Savings: 0.10 × 2,400 = $240.
- "How much more" means subtract: $960 − $240 = $720.