Common Core LiteracyGrades 9–10Science & Technical

RST.9-10.3: Following a Complex Multistep Procedure

Also written as CCSS.ELA-LITERACY.RST.9-10.3 · Cluster: Key Ideas and Details.

The Official Wording

Follow precisely a complex multistep procedure when carrying out experiments, taking measurements, or performing technical tasks, attending to special cases or exceptions defined in the text.

Common Core State Standards, Grades 9-10, Reading: Science & Technical Subjects · Read it at the source · Checked October 14, 2026

What RST.9-10.3 Means in Plain English

Ninth and tenth graders carry out a complex lab procedure exactly as written, including the special cases its instructions spell out. A Gram stain has four timed steps, but its most important line may be the exception that rules out a plate more than a day old.

In grades 6 to 8 (RST.6-8.3), students followed a multistep procedure precisely. Ninth and tenth grade make the procedure complex and add its exceptions. In grades 11 and 12 (RST.11-12.3), students also analyze their specific results using the explanations the text gives.

RST.9-10.3 I Can Statements

I can follow each step of a lab procedure exactly.
I can find the exceptions a procedure defines before I start.
I can decide whether my situation falls under an exception.

RST.9-10.3 Worked Example

The protocol has four timed steps and one exception, and the weak answer checks the steps but never reads the exception.

Read the Story

Gram stain, Biology Lab 7. Start from a heat-fixed smear: spread a small amount of culture thinly on a slide, let it air-dry completely, then pass it through a burner flame three times.Flood the smear with crystal violet for 60 seconds, then rinse gently with water. Flood it with Gram’s iodine for 60 seconds and rinse again.Decolorize: tilt the slide and add alcohol drop by drop only until the runoff is clear, usually 5 to 10 seconds, then rinse at once. This is the step most likely to ruin a result: too long and every cell turns pink.Counterstain with safranin for 45 seconds, rinse, blot dry and view under oil immersion. Gram-positive cells hold the violet and look purple, and gram-negative cells lose it and take up the pink.Exception: use only cultures 18 to 24 hours old. Older gram-positive cells can lose the violet and read as pink, so if your plate is older than 24 hours, streak a fresh plate and stain it the next day.

A short passage written for this page.

Question: A student stains a plate of Staphylococcus that was streaked 40 hours ago, sees pink cells and concludes the bacteria are gram-negative. Using the protocol, explain what the student should have done and what the slide can and cannot show.

Not Yet“The student did all the steps in order, crystal violet, iodine, alcohol and safranin, so the result is right. The bacteria are gram-negative because they are pink.”It checks only the order of the four steps and skips the exception, which rules out a 40-hour plate, and it ignores the decolorizing step the protocol flags as the likeliest to turn every cell pink.

Meets the Standard“The student should not have stained that plate. The protocol says to use ‘only cultures 18 to 24 hours old’ and, if a plate is older, to ‘streak a fresh plate and stain it the next day.’ This plate was 40 hours old, and older gram-positive cells ‘can lose the violet and read as pink,’ so pink cells cannot prove the bacteria are gram-negative. A second cause is possible too: if the alcohol ran past the point where the runoff was clear, ‘every cell turns pink.’ The student needs to stain a fresh culture, adding alcohol only until the runoff is clear.”It applies the exception to this exact case, names a second step that could cause the same error, and says what to do differently rather than only that the result was wrong.

Question Stems to Use

Which step has a time limit, and what happens if you miss it?Does the text name any case where the usual steps do not apply?Does this situation fall under that exception? How do you know?Which step does the text warn is easiest to get wrong?What would you do differently next time, step by step?

Common Mistakes with RST.9-10.3

Starting before reading to the end

Staining a two-day-old plate because the exception sits in the last line

Try this: Have students read the whole procedure first and box every exception, warning and time limit before they touch a slide.

Treating “until” as a fixed time

Pouring alcohol for a full 10 seconds when the runoff was clear at 4

Try this: Ask students to circle every “until” and “only” in the procedure and say what they will watch for at that step.

Trusting a result the exception rules out

“The cells are pink, so the bacteria are gram-negative.”

Try this: Have students list every condition the procedure sets for a valid result and check their run against each one before drawing a conclusion.

Where RST.9-10.3 Fits

Comes BeforeRST.6-8.3Follow a multistep procedure precisely in experiments, measurements and technical tasks.

AlongsideWHST.9-10.2Write up a procedure or experiment precisely enough for another reader to repeat it.RST.9-10.4Work out what key terms such as decolorize and counterstain mean in a specific lab context.

Comes NextRST.11-12.3Follow a complex procedure precisely and analyze the specific results using the text’s explanations.

Practice RST.9-10.3

Quick Check

Which step does the protocol say is most likely to ruin a result, and how?
Decolorizing. If the alcohol runs too long, every cell turns pink.
What exception does the protocol define?
Only cultures 18 to 24 hours old may be stained, because older gram-positive cells can lose the violet and read as pink.
What should a student with a 40-hour-old plate do?
Streak a fresh plate and stain it the next day.

RST.9-10.3: Other Names

RST.9-10.3CCSS.ELA-LITERACY.RST.9-10.3