Clue 1: Orient yourself
What can the replay show that the final score cannot?
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
What can the replay show that the final score cannot?
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: Researchers combine lineage labels, live imaging, and model organisms to turn hidden developmental events into visible evidence.
On your WebXam
Judging model-organism validity and imaging methods
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
Replay plus colored jerseys reveals the whole play
A replay preserves the order of a play, while jersey colors identify who moved where. Together they show both timing and the path of each participant.
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
Why do colored jerseys matter when players cross paths?
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
What question would require more than one camera angle?
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.
- 1What can the replay show that the final score cannot?
- 2Why do colored jerseys matter when players cross paths?
- 3What question would require more than one camera angle?
Tier 1 check
Finish with the everyday model
Use the everyday picture to answer today's question in plain words: What can the replay show that the final score cannot?
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: Time-resolved evidence reveals sequence.
Rule 2: Stable labels reveal cell lineage.
Rule 3: Different models and methods answer different questions.
Where the analogy stops: Imaging cells is limited by access, resolution, labels, and model differences.
Carry the previous idea forward
The same DNA can produce different outcomes because gene activity and developmental context can differ.
Today's technical takeaway
Researchers combine lineage labels, live imaging, and model organisms to turn hidden developmental events into visible evidence.
Now map the same rules onto biology
Choose a method to watch development
Colored jersey
Genetic or fluorescent lineage label
Replay
Live imaging over time
Final score
Endpoint anatomy or histology
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
DEV18-E1
Lineage labels mark a cell population and its descendants.
Why it matters: They answer where cells came from and what they became.
DEV18-E2
Live imaging records movement and cell behavior over time.
Why it matters: It can reveal order and timing.
DEV18-E3
Mouse and zebrafish models share important developmental mechanisms but are not identical to humans.
Why it matters: Model choice sets a limit on transfer.
Make the clinical decision
You are choosing a method for a seam-removal study.
The question is whether labeled seam cells die, leave the surface, or persist during the next six hours.
AUse stable lineage labels with live imaging and cell-state markers.
BUse only the adult skull endpoint.
CUse one unlabeled still image.
Choose the method set and cite the evidence for both time and identity.
Evidence required
DEV18-E1 + DEV18-E2 Claim ceiling
You may observe mechanism in the selected model. You may not assume every human embryo follows every model detail.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 18: Watching Development Happen
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
- is the study of changes in gene activity that do not change the itself.
- adds a methyl group that usually silences a gene; a study found 578 methylation positions associated with nonsyndromic CL/P, enriched in regulatory craniofacial regions.
If not, review
Today's new idea is only
Because we cannot film a human , scientists use model organisms plus and to watch each step, then reason carefully about what transfers back to a human.
Goal: Explain why scientists use model organisms (mouse, zebrafish) and plus to watch , and judge what each tool can and cannot tell us about a human .
Know by the end
- A is a non-human species studied because it shares key biology and is easier to observe; trust rests on homology, common descent making genes and steps comparable.
- The mouse truly fuses a secondary and its timing maps onto human weeks; the zebrafish is transparent and develops outside the mother but does not make a mammalian secondary palate, so some results need caution.
- permanently tags cells so their descendants can be found later; films development in real time.
- argued against the old cells-migrate-away idea, and revealed seam cells being squeezed out () as the main way the seam disappears.
1
Two model organisms
Model start: A is a non-human species studied because it shares key biology with humans and is easier to observe or experiment on.
- The mouse is the workhorse because its truly fuses and its timing maps cleanly onto human weeks, so a mouse mechanism usually ____ (transfers) to humans.
- The zebrafish is transparent and develops outside the mother, so you can ____ (watch) living cells, but it does not make a mammalian secondary , so some results need caution. This rests on ____ (homology).
2
Two seeing tools
- permanently marks cells so you can later find their ____ (descendants).
- films development in real time and revealed ____ () as the main way the seam disappears.
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: Because we cannot film a human , scientists use model organisms plus and to watch each step, then reason carefully about what transfers back to a human.
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
You are choosing a model to investigate one open question about Mateo's cleft: "did the medial edge cells fail to get extruded?" Decide whether you would use mouse or zebrafish, name the imaging tool you would pair with it, and write two sentences: one on what the model could show you, and one honest caution about what it could NOT tell you about a human.
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.
- Lan & Jiang 2015, Cellular and Molecular Mechanisms of Palatogenesis (Curr Top Dev Biol)
- Liu et al. 2016, Irf6 directly regulates Klf17 in zebrafish periderm and Klf4 in murine oral epithelium (journal link; use class excerpt if blocked)
- Schoen et al. 2017, MicroRNAs in Palatogenesis and Cleft Palate (Front Physiol)
- Claim: Scientists (can / cannot) directly watch a mammalian seam disappear.
- Evidence: One plus one imaging tool, and what it showed.
- Reasoning: Why combining models and imaging is more trustworthy than one alone, and what caution applies when moving from animal to human.
How this is graded (rubric)
For: You are choosing a model to investigate one open question about Mateo's cleft: "did the medial edge cells fail to get extruded?" Decide whether you would use mouse or zebrafish, name the imaging tool you would pair with it, and write two sentences: one on what the model could show you, and one honest caution about what it could NOT tell you about a human.
| 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 "You are choosing a model to investigate one open question about Mateo's cleft: "did the medial edge cells fail to get extruded?" Decide whether you would use mouse or zebrafish, name the imaging tool you would pair with it, and write two sentences: one on what the model could show you, and one honest caution about what it could NOT tell you about a human.".
- 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: Model organisms plus let us watch each step of and pin down which one failed. So a bold question: if we can see exactly which step fails and exactly when, could a scientist step in during the window and prevent a ?