Materials & Methods
Write a precise, past-tense record of exactly what you used and did, detailed enough that another person could repeat your investigation and get the same result.
Science only counts as evidence if someone else can repeat it. The Materials and Methods section is your promise that they can: it is a precise, past-tense record of what you used and what you did, with the amounts, times, and conditions that make the result possible to reproduce. It is a record of what happened, not a set of instructions telling the reader what to do. Notice the difference between a method and a procedure: a procedure is the how-to list you follow while working ('Add 5 mL of buffer'), while a method is the finished report of what was actually done ('5 mL of buffer was added'). Lab technicians read a methods section to run the same test again, peer reviewers read it to judge whether the work was done well, and forensic analysts write it so a court can trust that the evidence was handled correctly. When another team cannot reproduce a published result, the methods section is the first place everyone looks. Learn to write it well and your work stops being a story and starts being something others can check, trust, and build on.
- Common Core · WHST.9-10.2Write informative/explanatory texts, including scientific procedures and experiments, with precise, well-chosen detail.
- Common Core · RST.9-10.3Follow precisely a complex multistep procedure when carrying out experiments, taking measurements, or performing technical tasks.
- NGSS · SEP-8Obtaining, Evaluating, and Communicating Information: communicate scientific procedures and findings clearly enough that others can reproduce them.
- Ohio · Ohio ELA W.9-10.2Write to convey complex processes clearly and accurately using precise language and relevant, sufficient detail.
- AP · AP Bio SP 3Design and describe an experimental procedure, including the controls and measurements needed to test a hypothesis.
- Tell past-tense from command (imperative) writing: A method is written in the past tense as a record, so students first need to hear the difference between 'was added' and 'add'.
- Write an amount with its unit: Methods report exact quantities, so students must pair a number with a unit (5 mL, 2.0 g) instead of saying 'some'.
- Name the sections of a lab report: Students need to know Materials and Methods is one section, separate from Results and Conclusion, before deciding what belongs in it.
Prerequisites are inferred: pending teacher review.
Re-learn the skill with worked practice and clear examples.
Now write a methods section that another person could actually repeat. A reproducible method names the amounts, times, and conditions for every step. Use the checklist and the example below to find what a weak sentence is missing, then add it.
A student wrote this method sentence: 'We added salt to the water and stirred it.' Using the checklist, which detail is MOST needed to make it reproducible?
Reviewed| Checklist item | In the sentence? |
|---|---|
| Amount of salt | No |
| Amount of water | No |
| Stir time | No |
| Action (added, stirred) | Yes |
- A.Change 'added' to the past tense.
- B.The exact amounts (how much salt and how much water) and the stir time.
- C.The name of the student who did it.
- D.A sentence saying the salt dissolved quickly.
Show the worked solution ▾
Answer: B. The exact amounts (how much salt and how much water) and the stir time.
- Step 1: Read the checklist: The table shows the action is present, but the amount of salt, amount of water, and stir time are all missing.
- Step 2: Pick the reproducibility gap: To repeat this step, another person needs the exact amounts and the time; those are what the sentence lacks.
Why it's right: The checklist shows the amounts and the time are missing, and those are exactly the details another person needs to repeat the step, so adding them makes it reproducible.
- A: The sentence is already past tense ('added,' 'stirred'), so tense is not the gap.
- C: The person's name does not help anyone repeat the step.
- D: How fast the salt dissolved is a result, not a setup detail needed to repeat it.
Aligned to Common Core WHST.9-10.2: precise quantitative detail · reading level ~grade 9
Which rewrite of 'We heated the liquid for a while' is the BEST method sentence?
Reviewed- A.We heated the liquid until it looked ready.
- B.The liquid was heated to 60 C for 10 minutes.
- C.Heat the liquid for a while, then stop.
- D.The liquid got pretty hot after some time.
Show the worked solution ▾
Answer: B. The liquid was heated to 60 C for 10 minutes.
- Step 1: Name amount, time, and condition: A strong method gives numbers: what temperature and for how long, written as a record.
- Step 2: Compare options: Only 'heated to 60 C for 10 minutes' gives a specific condition and time in past tense; the others are vague or are commands.
Why it's right: A reproducible method states the condition and time as a past-tense record; '60 C for 10 minutes' gives both exactly so the step can be repeated.
- A: 'Until it looked ready' is a judgment, not a measurable condition, so it cannot be repeated.
- C: 'Heat the liquid' is a command (procedure), and 'for a while' has no number.
- D: 'Pretty hot' and 'some time' give no measurable amount or time.
Aligned to Common Core RST.9-10.3: precise multistep detail · reading level ~grade 9
A methods section reads: 'The samples were kept in the dark for 24 hours, then their mass increased by 3 g.' Which part does NOT belong in Materials and Methods?
Reviewed- A.'The samples were kept in the dark' (a condition).
- B.'for 24 hours' (a time).
- C.'their mass increased by 3 g' (a measured outcome).
- D.Nothing; every part belongs here.
Show the worked solution ▾
Answer: C. 'their mass increased by 3 g' (a measured outcome).
- Step 1: Methods hold setup, not outcomes: The condition (dark) and the time (24 hours) describe the setup. A measured change in mass is a result.
- Step 2: Find the misplaced part: 'Their mass increased by 3 g' is data that was measured, so it belongs in Results, not Methods.
Why it's right: Materials and Methods records the setup (a dark condition kept for 24 hours), but a measured mass increase of 3 g is an outcome that belongs in Results.
- A: Keeping samples in the dark is a condition, which belongs in Methods.
- B: The 24-hour time is a setup detail that belongs in Methods.
- D: It is not all correct; the measured mass increase is a result placed in the wrong section.
Aligned to NGSS SEP-8: keep methods separate from results · reading level ~grade 9
- A student revises a PLTW lab procedure into a past-tense methods section with every amount and time filled in.
- A lab group runs a weak methods paragraph through the amount/time/condition checklist and adds the missing numbers.
- A test-taker rewrites a vague sentence ('we waited a while') into a measurable record ('the tubes were left for 15 minutes at room temperature').
Fill these in as you work through the lesson.
- Method (past-tense record of what was done):
- Procedure (step-by-step how-to you follow):
- Reproducible (another person can repeat it and get the same kind of result):
- Condition (a controlled part of the setup (temp, light, time)):
A method is written in the tense as a record, not as an to the reader; it must name the amounts, times, and so the work is reproducible.
- Rewrite this command as a method: 'Add 5 mL of buffer to the tube.'
- List the three checklist questions a strong method answers for each step.
- Given 'we heated the liquid for a while,' name what is missing and rewrite it as a reproducible record.
Turn this weak sentence into a reproducible method: 'We put some salt in water and waited.' Amount of salt: ____. Amount of water: ____. Time: ____. Rewrite (past tense): ____.
The vocabulary of this topic, shown in the way you will meet it.