JOHN HAY BIOMEDICAL · HBS · ORIGINAL COURSE SUPPORT
Five tissue slides.
Record what you see.
A histologist gets a slide with a code number and no organ name, and still knows which of the four tissue groups it belongs to. Today you learn what they look at, and you record five slides the same way.
Make one product: five completed organizer panels, one per slide, plus one organization line for the stomach. Save both as one PDF. Paper or a document is fine. This page does not save answers.
Turn-in links for both sections · Print the five-panel organizer (PDF) · Organizer as a web page · February 9 daily directions
1. Learn the sorting rule
Reference R · The words you need
A cell is the smallest living unit of the body. A tissue is a group of similar cells, plus the material between them, that does one kind of job. Organs combine two or more tissue types. The stomach includes all four groups.
| Group | How the cells are arranged | What sits between the cells |
|---|---|---|
| Epithelial | Packed side by side in a sheet that covers a surface or lines a hollow organ. One side of the sheet faces open space, called a free surface. | Almost nothing. |
| Connective | Spread out, often far apart, in a material the cells make. | A lot of matrix: fibers, gel, liquid or solid. The matrix is made by the cells but is not alive itself. A fiber is a long thin strand in the matrix. |
| Muscle | Long cells lying side by side that shorten, or contract, to produce movement. | Thin partitions only. |
| Nervous | Neurons with signal-carrying extensions, plus supporting cells called glia. Some views show bundles of extensions. | Support cells and thin wrappings. |
The two sorting questions. For any slide, ask: (1) How are the cells arranged: a packed sheet, spread out in material, long strands, or cells with branching extensions? (2) What sits between the cells: almost nothing, a lot of matrix, or thin partitions? Then confirm the group with one specific feature you can see, such as a free surface, fibers, or crosswise stripes.
A nucleus is the dark, usually round part of a cell that holds its DNA. On a stained slide, nuclei are the easiest features to find, and where they sit tells you a lot. A striation is a fine stripe across a muscle fiber. The lumen is the open space inside a hollow organ or tube.
Magnification. Total magnification = eyepiece magnification × objective magnification. Most school microscopes have a 10x eyepiece and 4x, 10x and 40x objectives. Write the total with an x, and record the objective you actually used for your sketch.
Model M · Try the rule on a separate example
Magnification model: 15x eyepiece × 4x objective = 60x. 15x eyepiece × 40x objective = 600x.
Constructed reference model, not an actual microscope observation.
A completed panel for a slide that is not on today's list (simple squamous epithelium, a thin lining): Tissue type: simple squamous epithelium. Main group: epithelial. Total magnification: 15x × 40x = 600x. Sketch labels: flat cell outline; central nucleus. Observations: One layer of thin, flat cells fits together like floor tiles, with a rounded nucleus bulging near the middle of each cell. Almost nothing sits between the cells and the sheet has one free surface, so this is epithelial tissue.
Separate Model M hierarchy: one cardiac muscle cell → cardiac muscle tissue → heart → cardiovascular system → whole person. This is a reference example, not a second assigned line.
Check yourself: Your eyepiece is 15x and you are using the 10x objective. Write the total before opening the answer.
Check the magnification
15x × 10x = 150x. Switching to the 40x objective would make it 600x: the eyepiece stays the same, so the total changes only with the objective.
2. Read the five slide cards
Microscope route only, after teacher approval, supervision and equipment-specific directions. Card route: skip physical work; use the described 400x view.
Card route: use D3 elastic connective tissue and D4 neuron smear, or name the alternate card variant you chose. Never merge both variants into a claimed observation.
Each card describes what its slide usually shows at 100x and then 400x. Read the card before you look, so you know what to look for. If you have no microscope today, the card is your recording source: use the card's 400x view, write the magnification as 10x × 40x = 400x, sketch what the card describes, and write "from the described card" on that panel. Decide each card's group, and the feature that decides it, with Reference R's two sorting questions. A card-based panel is a supplied description, not your own observation. Your own slide may differ a little in color or in the direction of the cut. Record what you see.
D1 · Simple columnar epithelium
Often from the lining of the small intestine or stomach. At 100x: a single row of tall, narrow cells standing side by side like fence posts along an edge. The top of the row faces an open space, the lumen. At 400x: each cell has one oval nucleus, and most nuclei line up near the bottom of the row. Under the row is a thin boundary, and below that a looser, pinker tissue with scattered nuclei. In an intestinal example, pale, cup-shaped cells may sit between the tall cells.
D2 · Adipose tissue
Fat storage tissue. At 100x: many large round or many-sided shapes packed together like bubbles or a honeycomb. The inside of each shape looks empty or very pale, because the fat that filled the cell dissolved when the slide was made. At 400x: a small, flattened nucleus is pushed against the edge of each cell. Thin lines mark the borders between cells, and small blood vessels or thin fibers may run between them.
D3 · Elastic tissue
Elastic connective tissue. Many slide sets use the wall of a large artery or a neck ligament. At 100x: wavy, dark strands running mostly in one direction, packed in bundles. At 400x: the strands branch and join, and between them are only a few small, flattened, dark nuclei.
If your slide is labeled elastic cartilage instead, you will see cells sitting in small clear spaces with a dark network of fibers around them. That is also connective tissue. Copy the label your slide actually carries and describe what you see.
D4 · Nerve
Two kinds of nerve slide are common, so check your slide's label. Neuron smear, often from the spinal cord: at 100x, a few large star-shaped cells scattered across the field with many small dark dots around them. At 400x, each large cell has a big round nucleus with a darker dot inside it, and several thin extensions branch outward from the cell body. The small dots are the nuclei of support cells. Nerve cross section: at 100x, round bundles packed with many small circles. At 400x, each circle is one extension cut across, often with a pale ring around a dark center.
D5 · Skeletal muscle
Usually cut along the length of the fibers. At 100x: long, straight, cylinder-shaped fibers running side by side like cables. At 400x: many oval nuclei sit along the edges of each fiber, and fine stripes cross each fiber at a right angle to its length. The stripes are striations, and they are easiest to see at 400x.
E3 · Limits of the record
No patient record, reference slide or function measurement is supplied. These practice cards and your own observations show structure at one moment. They cannot support a diagnosis or any claim about a cohort patient, and they do not measure what the tissue is doing. Histologists do detect disease by comparing a sample with a known normal pattern and a clinical record; you have neither here.
3. Record five panels, then the organization line
Print the five-panel organizer, or copy its fields into your notebook. The fields match the PLTW Histology Organizer, so you can copy your entries onto the official organizer later if Mr. Mendoza directs it.
| Field | What to write |
|---|---|
| Tissue type and main group | The slide's name, then one of the four groups from Reference R. |
| Total magnification | Written as a product, eyepiece × objective, as in Model M. Use the objective you sketched at. For a card-based panel, write the card's 400x view: 10x × 40x = 400x. |
| Sketch | What fills your field of view. Label two features named on the D card, such as a nucleus, a fiber, a free surface or a stripe. Artistic skill is not part of the task. |
| Observations | Two sentences: how the cells are arranged, and what sits between them. Name the feature that decided the group. |
| Source | Microscope, or "from the described card" (a supplied description at 400x, not your own observation). |
Reference R · Five organization levels
A cell is one living unit; tissue is cells and surrounding material working together. An organ combines two or more tissue types. An organ system is organs working together. An organism is the whole living individual. The stomach wall contains smooth muscle tissue, built from smooth muscle cells. Smooth muscle is muscle without the crosswise stripes of skeletal muscle. The digestive system processes food; the stomach is one of its organs.
Use these facts to build the stomach line. The heart example in Model M is separate reference work, not another assigned line.
Then the organization line. Write the five levels in order, cell → tissue → organ → organ system → organism, with one example from the stomach at each level. The stomach lining, its muscle layers, the connective tissue that holds it together and the nerves that control it are all part of one organ.
Keep the claim within the evidence: Name the group and describe what you saw. Do not diagnose a disease, claim anything about a cohort patient, or state what the tissue is doing right now. E3 supplies no evidence for those claims.
Need a smaller first step?
Start with the slide in front of you. Open its D card. Write the tissue type and the magnification product first. Then sketch and label just the two features the card names. Choose the group last, using the two sorting questions.
For the organization line, start with the whole organ, the stomach, and work outward to the organ system it belongs to, then inward to one tissue and one cell.
Microscope steps, teacher-approved physical route only
Microscope route only, after teacher approval, supervision and equipment-specific directions. Card route: skip physical work; use the described 400x view.
- Start on the 4x objective. Put the slide on the stage with the label facing you and turn the light on low.
- Focus with the coarse knob until you see color, then center a clear region. Switch to 10x and refocus with the fine knob only.
- Record the tissue type and the magnification. Sketch and label two features.
- Switch to 40x using only the fine knob. Add anything you can now see.
- Write your two observation sentences. Return to 4x before you remove the slide.
Safety: carry the microscope upright with two hands. Hold glass slides by the edges and report a chipped or broken slide at once. Never use the 100x oil objective today. Wash your hands when you finish.
4. Check and turn in
Check that all five panels have all five fields, and that any panel from a described card says so and shows 400x. Check that your organization line has five levels in order with a stomach example at each. Each group you named must come from something you can see or something a D card describes.
Save the panels and the organization line together as one PDF. If you used paper, scan it clearly. Open only your section's assignment below. Upload, submit, and check the preview. Follow the due date shown there.
A saved PDF is not proof of upload or teacher acceptance. If access is missing, keep the same work and mark receipt pending. Card panels do not establish microscope participation or official PLTW completion.
Your section number is in the Schoology course title. If you cannot find it or upload your file, keep your work and tell me. Do not skip the work or create a second submission.
Carry forward: Keep your five panels. Tomorrow's practice asks where a structure is, not which tissue it is, so the two records stay separate. Later in the unit you will look at more slides and add to the same kind of record.
How this supports PLTW
This original practice supports the microscope portion of HBS Activity 1.1.3, Held Together by a Thread. The official activity asks for five slides and supplies a four-panel organizer; this route gives you a clearly labeled fifth panel and a described card for every slide. Open your section's handout page below for the official activity, the PLTW Histology Organizer and your cohort patient chart. Those records stay in Schoology.
This practice does not complete an official PLTW activity. If a presentation, video or record will not open, tell me which one. Do not fill the gap with a guessed result.