Clue 1: Orient yourself
Why can the scenery move only during the blackout?
Use the labels and the picture's left-to-right, near-to-far, or before-and-after order. Name only what you can point to.
The question
Why does the timing of a disruption change which part of the face is affected?
Why it matters: The face forms through a timed sequence of growth, movement, and joining. Locating the missed step helps researchers ask a testable question instead of treating every cleft as the same process. Today you practice the professional reasoning behind that work: A developmental risk matters most when it acts during the short window for the process it can disrupt.
On your WebXam
Reasoning about critical-window timing and irreversibility
For life
To find the cause, change one thing and watch what changes.
Principle: Same look, different cause
Five principles we return to
Having it is not using it
Same instructions, different switches
Same look, different cause
Change one thing and watch
Boss or doorman?
Decides the result or only allows it
Held down, not gone
Remove the brake and it returns
Many roads, one ending
One result can begin many ways
Try the everyday version first
A theater door closes after one scene change
A stage crew may have one short blackout to move scenery before the audience sees the next scene. When that window closes, later work must use the set already in place.
Do not jump to the biology yet. Treat the picture as a small system. Track its parts, follow one change at a time, and keep more than one explanation open until the picture supplies a way to separate them.
Clue 2: Trace one change
What happens if the crew arrives after the curtain opens?
Follow one object, stage, or path. Point to the first place where the situation changes instead of jumping to the ending.
Clue 3: Keep the cause open
How could the same delay matter in one scene but not another?
List more than one explanation that still fits. Name the extra observation that would help you separate those possibilities.
Now inspect the illustration
Work from the visible evidence. A useful answer names the part of the picture that supports it and leaves unknown causes open.
- 1Why can the scenery move only during the blackout?
- 2What happens if the crew arrives after the curtain opens?
- 3How could the same delay matter in one scene but not another?
Tier 1 check
Finish with the everyday model
Use the everyday picture to answer today's question in plain words: Why does the timing of a disruption change which part of the face is affected?
You can complete today's required check without opening the technical details below.
Ready for the real names? Optional tier 2
Technical rules and limits
Rule 1: Some changes are possible only during a short interval.
Rule 2: Timing and target process must overlap.
Rule 3: After the window closes, later development builds on the existing structure.
Where the analogy stops: Biological windows can overlap and vary; they are not controlled by a stage clock.
Carry the previous idea forward
A cleft pattern narrows the failed developmental checkpoint, but it rarely identifies one unique cause.
Today's technical takeaway
A developmental risk matters most when it acts during the short window for the process it can disrupt.
Now map the same rules onto biology
Compare lip and palate critical windows
Blackout begins
Developmental process becomes possible
Scene change
Growth, elevation, or fusion event
Curtain opens
Critical window closes
Educational illustration, not a clinical photograph. Use the labels and evidence cards to make the biological claim.
Mateo's case file: evidence supplied in this lesson
DEV15-E1
Upper-lip fusion occurs earlier than completion of secondary-palate fusion.
Why it matters: The two structures have different timing windows.
DEV15-E2
A disruption must overlap a sensitive process to affect that process directly.
Why it matters: Exposure timing is part of causal reasoning.
DEV15-E3
After a cleft is established in utero, later normal growth does not automatically fuse the gap.
Why it matters: Subsequent development builds around the open structure.
Make the clinical decision
You are reviewing an exposure timeline without naming the exposure.
Exposure A occurred after upper-lip closure but during palatal fusion. Exposure B occurred before both windows.
APrioritize A for a direct palate-window hypothesis, while keeping other explanations open.
BClaim A directly caused Mateo's cleft lip.
CClaim timing never matters.
Choose the timing hypothesis and cite the window evidence.
Evidence required
DEV15-E1 + DEV15-E2 Claim ceiling
You may judge timing compatibility. You may not prove causation from timing alone.Go deeper Optional tier 3
Everything required for today is above. Open these only if you want the explainer, source trail, or download files.
The everyday model and Tier 1 check are the complete required path for this lesson.
Use these checks to keep your place. They are not turned in through the portal.
Check off as you finish
- Worked through the everyday picture and answered its three questions.
- Completed the Tier 1 check in plain words.
Turn in: Developmental lesson 15: Critical Timing Windows, When the Door Closes
Go to Schoology to turn this in.
Submit one PDF. Put your first and last name in the document header. Name the file: FirstName LastName - Assignment Title - YYYY-MM-DD.pdf.
Open Schoology PDF upload helpIf you cannot get in, see Mr. Mendoza. Do not skip the work.
Optional legacy technical materials Open only if you want the original notes, vocabulary, artifact, and CER work
Before this page, you should know
- The normal build order is: week 4 to 6 lip , week 6 shelf growth, week 8 shelf elevation, weeks 8 to 12 shelf and fusion.
- A lip points to a failure of step 1 (medial nasal plus maxillary ); a cleft only points to a failure of palate growth, elevation, or fusion.
Today's new idea is only
Each lip and step runs only inside a narrow critical window, and once that window closes the closure machinery shuts off, so a left open becomes irreversible by normal development.
Goal: Explain that each lip and step has a narrow critical window, and that once a window closes the cannot be undone by later development.
Know by the end
- The lip closes (medial nasal plus maxillary ) during human weeks 4 to 6.
- The secondary grows, elevates, and fuses during human weeks 6 to 12, with complete by about week 12.
- After the window, the face keeps growing larger but does NOT run the steps again; the closure tools (MEE, peel-away, ) are only on during the window.
- A left open when its window closes is irreversible by normal development; growth is not .
1
The fusion calendar
Model start: Each step has a critical window: a limited stretch of time when that step can happen at all. Miss the window and the step does not run later.
- The is human weeks ____ (4 to 6).
- The is human weeks ____ (6 to 12), with complete by about week ____ (12).
2
Why the deadline is real
- The closure tools (MEE, peel-away, the switch) are active during the window and then ____ (shut off).
- This makes a , once the window closes, ____ (irreversible) by normal development; the face grows bigger, but growth is not .
Everything you need for today is on this page. These links are optional.
What to read
Read the short plain-language explanation written for this lesson. Plain-language explainer for this lesson
Why this source matters
This explanation gives you the background for today's idea without making you decode a research paper: Each lip and step runs only inside a narrow critical window, and once that window closes the closure machinery shuts off, so a left open becomes irreversible by normal development.
Words to unlock first
Reading moves
- Skim the title and abstract first to get the gist.
- Circle the one sentence that states the main claim.
- Box the evidence the authors give for that claim.
- Mark one sentence that confuses you, and move on.
Stop point
Stop after the final 'Use it now' section. The research citations are available separately for advanced readers.
Your output
Write one claim-evidence sentence: state the main idea, then name the example or evidence that supports it.
Where this fits
Tested on (Ohio WebXam)
Genetics of Disease · 072130
PLTW lesson
MI · Developmental domain · PLTW PBS 072110
WebXam domain
Molecular and Genetic Technology
Evidence to produce
Build a simple timeline for Mateo. Mark the lip window (weeks 4 to 6) and the palate window (weeks 6 to 12). Then write two sentences: (1) the latest week by which his lip-and-palate closure had to succeed or fail, and (2) why a doctor cannot expect his cleft to close on its own after birth, using the word window and the idea that the fusion machinery has shut off. Do not name a diagnosis.
Lab / skill
Principles of Biomedical Science (PBS)
Everything required for today's decision is already in the case file and plain-language explainer. The links below are original papers and database records for teachers and advanced readers, not assigned student reading.
- Claim: A becomes locked in once its critical window closes.
- Evidence: In Model 2, the late clefted because its shelf arrived ____ the window, when the machinery had ____.
- Reasoning: Because the closure tools only run during the window, a structure left open after the window will ____.
How this is graded (rubric)
For: Build a simple timeline for Mateo. Mark the lip window (weeks 4 to 6) and the palate window (weeks 6 to 12). Then write two sentences: (1) the latest week by which his lip-and-palate closure had to succeed or fail, and (2) why a doctor cannot expect his cleft to close on its own after birth, using the word window and the idea that the fusion machinery has shut off. Do not name a diagnosis.
| Criterion | Proficient | Developing | Beginning |
|---|---|---|---|
| Complete | Every required part of the artifact is present and filled in. | Most parts are present, but one is missing or left blank. | Several parts are missing. |
| Accurate | The science and data are correct and match the evidence. | Mostly correct, with a small factual slip. | Key science or data is wrong. |
| Scientific reasoning (CER) | States a claim, backs it with specific evidence, and explains the reasoning. | Has a claim and evidence, but the reasoning is thin or missing. | Gives an answer with no evidence or reasoning. |
| Professional communication | Clear, organized, and labeled the way a clinician or scientist would write it. | Readable but disorganized or missing labels. | Hard to follow. |
| Submitted | Turned in through the route named under Submit here and confirmed. | Turned in, but in the wrong place or unconfirmed. | Not turned in. |
How the model answer scores against this rubric
- CompleteProficient: Nothing is left blank: the model fills every part of "Build a simple timeline for Mateo. Mark the lip window (weeks 4 to 6) and the palate window (weeks 6 to 12). Then write two sentences: (1) the latest week by which his lip-and-palate closure had to succeed or fail, and (2) why a doctor cannot expect his cleft to close on its own after birth, using the word window and the idea that the fusion machinery has shut off. Do not name a diagnosis.".
- AccurateProficient: Every number and claim matches the case evidence.
- Scientific reasoning (CER)Proficient: It names a claim, cites the specific evidence, and explains the reasoning, not just the answer.
- Professional communicationProficient: It is organized and labeled like a real chart note.
- SubmittedProficient: It would be attached to your class form or handed in, and confirmed.
What's next: We now know the face has narrow closure windows, and those windows are when it is most fragile. If the is most vulnerable during these weeks, can something from outside the embryo reach in during the window and change whether the face forms correctly?