Grade 5 · Math · Fractions
The error sheet: mark somebody else's work
A worksheet of 10 worked answers, 6 of them wrong
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A sheet of answers already written out. The student judges each one and names the mistake in their own words. Every wrong answer on it came from a real student in an earlier year.
This page is exactly what a teacher's published work will look like. Only the teacher is not real yet.
What the student does
- 1
Read the answer as it stands
Ten worked answers, six of them wrong. At this stage the student is not solving anything, only reading.
- 2
Decide: right or wrong
One mark against each one. There is no third box and no comfortable place to hesitate.
- 3
Name the mistake in their own words
One line under every wrong answer. A student who can name the mistake stops making it.
- 4
Redo it properly
Once the mistake has a name, the correct working goes beside it, so wrong and right stay on one page.
What's inside
- 10 worked answers, 6 of them wrong
- A writing line under every answer
- A teacher page giving the reason behind each mistake
Outcomes
Tells a right answer from a wrong one in same-denominator addition without redoing the work.
Names the mistake: adding the denominators, leaving the answer unsimplified, or mistaking two forms of one number for two numbers.
Writes the correct working beside the wrong answer and points at the step that went off.
What the teacher focused on
I have kept my students' mistakes in one notebook for nine years. This sheet is that notebook, handed to the student instead of staying with me.
Teaching strategies
- Marking as a skill that is taught, not a result that is awaited
- The recurring mistake as the lesson's raw material
- The student's words before the rule's words
He turned down a page of blank problems, and left the tick and cross off the sheet. A student solving ten problems can repeat one mistake ten times without noticing. A student judging somebody else's answer reads the mistake from the outside.
Questions from inside it
- 1A student wrote: 3/8 + 4/8 = 7/16. Is he right? If not, what did he do?
- 2A student wrote: 5/9 − 2/9 = 3/0. Explain why this cannot be an answer at all.
- 3Two answers to the same question: 4/10 and 2/5. Which one is wrong?
Curriculum
- Grade
- Grade 5
- Subject
- Math
- Unit
- Fractions
- Taught in
- Jordan
Where this lesson sits in the curriculum
The same lesson appears in these countries' curricula. One page, five paths to it.
When to use it
The explanation
The denominator says how many parts the whole was cut into; the numerator says how many we took. Adding and subtracting do not re-cut the whole, so the denominator holds and only the numerator moves. And if the answer's top and bottom share a factor, the answer is right but unfinished — which is not the same thing on an exam paper.
Common mistakes it catches
Subtracting the denominators gives a denominator of zero — a whole cut into no parts at all. Ask the student to draw that, and they stop at the first line.
They are one number, and 2/5 is 4/10 in its simplest form. An answer is judged by its value, not by its shape, and the question that settles it is: do these two cover the same amount of the bar?
6 and 8 both divide by 2, so the simplest form is 3/4. Train one habit after every answer: do the top and the bottom share a factor?