How this EZ grader works
A paper EZ grader is a slide chart. You pull the card until the window shows the number of questions on the test, and each line lists a number missed next to its percent score. It’s quick once the right row is lined up, and it’s easy to misread a line when you’re on your fortieth paper of the night. This version does the same lookup without the squinting: type the number of questions and the number wrong, and the score and letter grade appear right away, with the whole chart for that test underneath.
Grading a stack? Leave the number of questions alone and change only the number wrong for each paper. The chart scrolls to the matching row and marks it, so you can also read scores straight off the chart and skip the typing.
EZ Grader is the name a lot of teachers use for any of these slide charts. GradeDuck isn’t affiliated with any company that makes or sells a product called EZ Grader. It’s an independent calculator that does the same math.
The formula
For a test scored in points, swap questions for points: (Total points − Points missed) ÷ Total points × 100. Points mode does exactly that, and it steps the chart by the value of one question, so every row is still one more wrong answer.
Each wrong answer costs 100 ÷ the number of questions. On a 25-question test that’s 4 points apiece. On a 30-question test it’s 3.33, which is why 30-question tests throw off so many decimals and why the decimal setting is there.
Paper charts usually print whole numbers, and not all of them handle the leftover the same way: some round 86.67 up to 87, others drop the decimal and print 86. Near a cutoff that one point is the gap between a B and a B+. Pick whole numbers if that’s how you report grades, or keep one decimal so you can see how close a paper sits to the line before you round it yourself.
Two worked examples
A short quiz. 25 questions, 3 wrong. The student got 22 right, and 22 ÷ 25 = 0.88, so the score is 88%, a B+ on the standard scale. One more miss drops it to 84%, still a B.
A test with 2.5-point questions. 40 questions at 2.5 points each is a 100-point test. A student who misses 7 loses 17.5 points, and 82.5 ÷ 100 = 82.5%, a B-. Give half credit on one of those answers and they’ve missed 6.5 questions, or 16.25 points, which makes it 83.75%, a B. In points mode you’d enter 100 total points, 2.5 per question, and 16.25 points missed.
How many can a student miss?
This is the question students ask the second a test comes back. The table shows the most questions someone can miss and still earn each letter, using the cutoffs GradeDuck uses everywhere: 93 for an A, 83 for a B, 73 for a C, and 65 for a D.
| Questions | Each wrong costs | A (93+) | B (83+) | C (73+) | D (65+) |
|---|---|---|---|---|---|
| 10 | 10 points | 0 | 1 | 2 | 3 |
| 20 | 5 points | 1 | 3 | 5 | 7 |
| 25 | 4 points | 1 | 4 | 6 | 8 |
| 30 | 3.33 points | 2 | 5 | 8 | 10 |
| 40 | 2.5 points | 2 | 6 | 10 | 14 |
| 50 | 2 points | 3 | 8 | 13 | 17 |
Short quizzes swing hard. On a 10-question quiz a single wrong answer is a 90, an A-, so one slip is the difference between an A and an A-. On a 50-question test a student can miss three and keep the A. If a whole class lands low, you can curve the test before you record it.
Averaging several test scores
The Test average tab is for the end of a unit or grading period, when you want one number from a row of tests. Type the scores separated by commas or spaces. Half points are fine (87.5), and so are raw points written as a fraction: 45/50 counts as 90%.
Say a student has 88, 92.5, 76 and 95. They add up to 351.5, and 351.5 ÷ 4 = 87.875%, shown as 87.88%, a B+. If the class drops the lowest test (Canvas, for one, has a drop-lowest rule for assignment groups), the 76 goes and 275.5 ÷ 3 = 91.83%, an A-. One dropped score moves the average almost four points, because the 76 sat 12 points below the next-lowest score.
The average treats every test the same. That’s right when each test is out of 100 or the syllabus says tests count equally. If a 50-point quiz and a 200-point unit test share a category, a straight average gives the quiz too much say. Add up points earned and possible instead, or use the grade calculator’s What-if tab, which can also drop the lowest score by points.
Half credit on one test. In the One test tab, type a half for the number wrong, such as 2.5, and tick Half-credit rows in chart to get a chart that steps by half a question. On a 20-question test, 2.5 wrong is 17.5 ÷ 20 = 87.5%, a B+.
When your gradebook disagrees
- Different cutoffs. Plenty of schools use a 10-point scale (90 A, 80 B, 70 C, 60 D) with no pluses or minuses. The percent here is still right; only the letter changes. The scale GradeDuck uses, and where it comes from, is on the methodology page.
- Rounding. The letter comes from the unrounded score, so an 89.6 is a B+ here even when the whole-number display shows 90%. If you round 89.5 up to an A-, that call is yours to make.
- Questions worth different points. When a test mixes 1-point multiple choice with 5-point short answers, counting wrong answers can’t give you the score. Add up the points missed and use points mode with 1 point per question.
- Extra credit. Scores above 100% aren’t supported. Take bonus points off the points missed, or add them in your gradebook.
- One test isn’t the class grade. To see how this score fits with homework and quizzes, use the grade calculator. If a final is still coming, the final grade calculator shows what a student needs on it.