The four methods
| Method | How it works | Effect |
|---|---|---|
| Highest score to 100 | Add (100 − top score) to every score | Same bump for everyone, set by the top score |
| Add points | Add the same number of points to every score | Simple and predictable |
| Square root | New score = 10 × √score | Low scores rise most; 100 stays 100 |
| Target average | Add (target − current average) to every score | Class average lands where you want it |
Worked example
The example class's top score is 90, so "highest score to 100" adds 10 points to everyone: 55 becomes 65 and 90 becomes 100. With the square root curve instead, 55 becomes 74.2 and 90 becomes 94.9. The average of the ten example scores is 72.1%.
Common questions
- What are the common ways to curve grades?
- Adding the same points to everyone (a flat curve), raising the highest score to 100 and adding that difference to all, the square root curve (10 times the square root of the score), and shifting scores so the class average lands on a target.
- How does the square root curve work?
- Each score becomes 10 times its square root. 64 becomes 80, 81 becomes 90 and 100 stays 100. Low scores rise the most, and nobody goes over 100.
- Is it fair to curve by the highest score?
- It depends on one student. If the top score is an outlier, everyone gets only a small bump. Many teachers use the second-highest score or a target average instead.
- Should curved scores go over 100?
- That's the teacher's call. Turn on the cap to stop any curved score going above 100.