Line graphs connect measurements across an ordered variable, often time. Evidence can concern an increase, decrease, stable interval, peak, minimum, fluctuation, convergence, divergence, or crossing.
What the SAT is testing
- Command of Evidence
- A supplied claim or point is evaluated with the textual or quantitative evidence that best supports, illustrates, weakens, or challenges it.
Core concept
Read points in order and describe only the pattern the values earn. A small change is not automatically a surge, and one interval does not establish a trend across the full period.
Evidence distinctions
Point
One value at one position. Example: Week 2: 46
Interval
Change between adjacent positions. Example: 46 to 59
Trend
Pattern across the stated scope. Example: Rises through week 3, then levels off
Step-by-step strategy
Claim-first evidence method
- Identify
State the exact claim, including its population, condition, direction, and qualification.
- Predict
Ask what evidence would look like if the claim were true—or what would challenge it.
- Locate
Select only the text or data relevant to that predicted relationship.
- Compare
Evaluate direction, scope, directness, and required assumptions across choices.
- Verify
Check the chosen wording and every cited value against the stimulus.
Visual and data-reading strategy
- Material A
- Material B
View chart data
| Series | Measurement point | Sensor reading |
|---|---|---|
| Material A | Hour 1 | 30 |
| Material A | Hour 2 | 42 |
| Material A | Hour 3 | 55 |
| Material A | Hour 4 | 61 |
| Material B | Hour 1 | 60 |
| Material B | Hour 2 | 54 |
| Material B | Hour 3 | 48 |
| Material B | Hour 4 | 43 |
Worked example
Apply 3-6
Synthetic sensor readings for two materials across four hours are A: 30, 42, 55, 61 and B: 60, 54, 48, 43.
Question: Which evidence supports the claim that the materials' readings converged?
- Their gap narrowed from 30 at hour 1 to 18 at hour 4.
- Material A rose by 12 during the first interval.
- Material B was higher at every hour.
- Their combined hour-4 reading was 104.
- Step 1
Convergence means the series move closer together.
- Step 2
Compare their gaps at the start and end.
- Step 3
Use the gap, not an isolated increase or total.
Why each choice works or fails
- Correct: 30 narrows to 18.
- One-series fact does not establish convergence.
- Relative order alone does not show the gap changed.
- A sum does not measure distance between series.
Common traps and wrong-answer patterns
Mini check
Values are 18, 25, 31, 29, 24. Which description is accurate?
- Steady decrease
- Increase to a peak, then decrease
- Constant
- Decrease then increase
Show answer and explanation
Answer: B
The series rises through the third point, peaks at 31, and then declines.
Key takeaways
What to remember
- Match every trend to a stated series and interval.
- Use exact points, not line steepness, as evidence.
- Distinguish one segment from a whole-period pattern.
- Converge, diverge, peak, and fluctuate have precise meanings.
Put these notes into practice
Apply the ideas with SAT-style questions, then reinforce key details with flashcards.