The worksheets themselves are in German – just as in class. The editor is only available in German so far.
Mistake detective – worksheets to print
Check other children's calculations: find typical mistakes – a forgotten carry, plus before times, a decimal comma as a separator –, say what went wrong and calculate it correctly.
- Choose the number of tasks and the difficulty yourself
- With an answer sheet and, if you like, a QR code to the answers
- At three levels (★ to ★★★) and as group A and B
- As a single worksheet or as a task on a mixed worksheet
Mistake detective: explained simply
Be a mistake detective: check a calculation or a worked solution, correct an error and explain what went wrong.
How to work it out
- Calculate the problem yourself first or check each line separately. A suggested solution may also be correct.
- Find the first incorrect step. Later errors may just follow from it. Explain your correction using the relevant rule.
An example, step by step
Someone writes 3 + 4 · 5 = 7 · 5 = 35. What is wrong?
- They calculated 3 + 4 first, but multiplication takes priority here.
- The correct first step is 4 · 5 = 20.
- Then 3 + 20 = 23. The mistake was ignoring the order of operations.
Understand other variations
Other kinds of mistakes
Depending on the task, check crossing tens, carries, decimal separators or common denominators. Explain not only the correct answer but also what was confused in the incorrect step.
Your turn
Someone writes 1/2 + 1/2 = 2/4. Explain the correction.
Show the answer and method
With equal denominators, add only the numerators. 1/2 + 1/2 = 2/2 = 1. Two halves make a whole.
Ready-made worksheets: Mistake detective
Click the picture to see the worksheet large and print it. “Use” opens it in the editor.