While the use of OMR (Optical Mark Recognition) sheets significantly simplifies large-scale data collection and exams, the process is only as reliable as the accuracy of how the sheets are filled and handled. Many answer sheets are rejected not because of wrong answers, but because of avoidable mistakes in filling, marking, or handling. This guide outlines the most frequent errors and how to avoid them.
When a sheet is mis-filled, mis-handled or improperly marked, the reading software may either fail to read it or reject it entirely — causing wasted effort, missed results or invalidation.
Here are typical errors that candidates make — and how you can avoid them:
Many candidates skip instructions in their rush to start answering questions, missing key directions like “Use blue/black ball-point pen”, “Do not do rough work on sheet”, or “Fill Roll. No before answering”.
Tip: Spend the first minute reading the sheet instructions – it can save your entire paper.
This is one of the most serious mistakes: If you fail to mark your roll number correctly, or skip it altogether, the OMR scanner cannot identify you and your sheet may be discarded.
Tip: After filling roll number bubbles, double-check the printed number (or handwritten if required) matches your assignment.
Using a fountain pen, gel pen, or wrong coloured ink when the instructions specify a ball-point pen in black or blue can lead to mis-reads or rejection.
Tip: Use a black or blue ball-point pen (or HB pencil if allowed), and avoid smudging or blotting.
If you mark more than one bubble for a single choice question, or leave the bubble only partially filled, or mark outside the allowed area, the OMR scanner might treat it as invalid or wrong.
Tip: Fill the bubble completely and neatly, avoid stray marks.
Doing rough calculations on the OMR sheet itself or writing slogans, or making notes outside the allowed areas may appear as stray marks and interfere with scanning.
Tip: Always use the rough sheet provided; keep the OMR sheet clean.
In exams where multiple copies exist (original + carbon copies), some candidates inadvertently submit the wrong one or keep the original with them, rendering their submitted sheet unreadable.
Tip: Verify with the invigilator which sheet is to be submitted.
It’s not just the candidates—exam centres and staff also make errors that compromise OMR processing.
Signing or stamping too close to the index points (corner markers) which are critical for scanner alignment.
Folding, stapling, punching or otherwise damaging OMR sheets before scanning.
Packing or storing sheets in improper conditions causing creases, smudges or distorted images.
Tip for staff: Ensure OMR sheets are kept flat, clean, and handled exactly as per instructions from the printing/scanning vendor.
Read the instructions before you start.
Use the correct instrument (pen/pencil) as directed.
Fill your roll number, booklet series, answer bubbles with precision and care.
Keep the sheet clean — no rough work, no stray marks, no foldings.
For invigilators: Check the sheet condition, confirm marking instrument, ensure no damaged sheets go into scanning.
By avoiding these mistakes, you give yourself the best chance of your responses being captured accurately and your effort being rewarded.
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