How to Check Your Answers in IGCSE Physics

Use this checking routine in the final minutes of any IGCSE Physics exam to recover marks you would otherwise lose.

The 5-point checking routine

1. Check every calculation for arithmetic errors

Re-enter key calculations on your calculator. Common errors:

• Typing 2.5 instead of 25 (decimal place error).
• Dividing when you should multiply (formula rearrangement error).
• Using the wrong row from a data table.

2. Check every unit

Scan every numerical answer. Does it have a unit? Is the unit correct? Common missing or wrong units:

• Writing “m” instead of “m/s” for speed.
• Writing “J” instead of “W” for power.
• Giving resistance in V instead of ohm.

3. Check unit conversions

If you converted units during a calculation, verify the conversion:

• g to kg: divide by 1000.
• cm to m: divide by 100.
• mA to A: divide by 1000.
• minutes to seconds: multiply by 60.

4. Check that you answered the question asked

Read the first line of each question again. Did you:

• Give the number of points requested? (“State two factors” needs two.)
• Answer in the correct format? (“Draw” means a diagram, not words.)
• Answer about the right quantity? (Did the question ask about current, not voltage?)

5. Check for blank questions

Scan the paper for any unanswered questions. Even a brief attempt is better than a blank. For multiple choice, there is no penalty for guessing.

What NOT to do during checking

• Do not rewrite answers that are already correct.
• Do not add extra information to answers that are already scoring full marks. Extra incorrect information can lose marks.
• Do not second-guess well-reasoned explanations based on exam nerves.

The “does my answer make sense?” test

For calculation answers, ask whether the number is physically reasonable:

• A speed of 300 m/s for a walking person is wrong.
• A current of 500 A through a school laboratory circuit is wrong.
• A mass of 0.002 kg for a car is wrong.

If the number does not make physical sense, re-check the calculation.