Introduction to Human Tissues: How are Tissues Classified?
In this inquiry investigation, students will use microscopes to observe slides of unknown tissues representative of the major groups found in the human body and then draw their observations in a science notebook. They will then work in groups to develop unique classification schemes for the tissues that are presented to the class. Finally, they will use their texts as a reference, comparing their classification schemes with the one that will be used in class and updating their science notebooks. The lesson is intended to be completed at the beginning of a histology unit to help students discover similarities and differences between the tissue types and to introduce the vocabulary of the major tissue groups.
1) Observe and draw the major tissue types, recognizing patterns.
2) Collaborate in a group to reach a consensus as to the classification of tissues, based upon those patterns.
3) Begin to develop their own definitions for the various tissue types.
3) Organization of data/ideas
1)Different tissues are made of different types of cells (morphology of cells).
2) Similarities within tissue types can be visualized.
3) Tissue form relates to function.
1) Epithelial tissue (simple/stratified, cuboidal, squamous, columnar, pseudostratified, transitional)
2) Striated/skeletal muscle, smooth muscle, cardiac muscle
3) Connective tissue (blood, bone, adipose, areolar, reticular, cartilage - types)
4) Neuron & neuroglia
5) Apical surface & basement membrane
6) Matrix & fiber (types)
Context for Use
Depending on the number of slides viewed, the investigation could take 2 to 3 50-minute class periods. Students should have previous experience with microscopes, observational drawing, and cooperative groups.
Another application of this investigation is to use the same method to teach classification of plant, animal, protist, and bacterial cells.
Resource Type: Activities:Lab Activity
Grade Level: High School (9-12)
Description and Teaching Materials
- Microscopes (I use about 12 for a class of around 20 students)
- Prepared slides of various tissue types
- Suggested tissues to use are striated muscle, smooth muscle, cardiac muscle, simple squamous epithelium (lung), simple cuboidal epithelium (gland), simple columnar epithelium (intestine), stratified squamous epithelium (skin), pseudostratified epithelium (trachea), transitional epithelium (bladder), blood, bone, reticular connective (spleen), cartilage (hyaline, elastic, fibrocartilage), neuron, neuoglia (cerebrum).
- Student whiteboards or large papers and markers
- Science notebooks, pencils, and colored pencils
- 3" x 3" posterboard squares
- Reference texts
Investigation Set-up (for Teacher)
*Students should have no previous knowledge of tissue types.
1) Create 3" x 3" squares out of posterboard, one for each student. These will help guide them in their tissue drawings and ensure that the cells they observe are drawn large enough.
2) Select the tissue slides you would like to focus on for the investigation. A few from each of the major groups (muscle, connective, epithelial, nervous) is necessary.
3) If the slides have labels on them, cover the labels with paper and/or tape and put a letter on each piece of tape (A., B., C., etc.).
4) Set up each slide on a microscope, with many scopes scattered throughout the room. Focus each scope on the tissue you want the students to observe. For example, the intestine has many tissue types in it, but it works well to focus the students on the simple columnar epithelium in the intestine. You will probably have to use different magnifications for the various tissue samples.
1) Students are to turn to a blank page in their science notebooks and write in the heading, "Observing and Classifying Tissues." As a class, discuss preconceptions of what a tissue might be.
2) There are __# of tissue samples around the room. Students are to rotate to all the microscopes and draw what they observe in the entire field of view in their science notebooks. Students should not move the slide or adjust the coarse adjustment knob.
- Label each drawing with the letter on the slide you are observing.
- Before drawing what you see, trace your posterboard square into your notebook. This entire area should be filled by your drawing.
- Pay attention to small details and transfer them into your drawing as best as possible. Colors matter!
- Be aware of any patterns you encounter as you draw and compare various tissues. Label/note any similarities and/or differences between tissues on your drawings as you work.
- Label each drawing with the total magnification used to view the specimen.
3) Once all students have completed their drawings, break them up into groups of 3 or so students. In their groups, students should discuss the patterns they observed within the tissue types and discuss how they might start to group some of the tissues together. On a whiteboard or piece of large paper, the group needs to develop a diagram that displays their classification scheme. Diagrams should also go into their science notebooks. (Allow 15 minutes or so for this portion.)
4) Each group presents their diagram to the class, with justification. Once all groups have presented, the class should discuss which diagrams they agree/disagree with, and why. Answer Analysis Questions.
5) Remaining in groups, allow students to get a textbook or other reference and try to match their drawings to the actual names of the tissues. Students should write their best prediction next to each drawing. Class discussion of the choices should follow.
6) Teacher reveals the actual identities of the tissues and students record them in their notebooks.
7) The teacher finally distributes an outline for tissue classification (see attachment below) and works with the students to complete the first tissue information together. The remainder of the outline can be completed in student groups or as homework.
Analysis Questions (to be completed in the science notebook after Step #4 above)
3 What are 3 similarities amongst your classification scheme and the others in class?
2 What are 2 differences between your classification scheme and the others in class?
1 Describe 1 challenge you discovered in classifying tissues. Tissue Classification Outline (Microsoft Word 41kB Aug31 08)
Teaching Notes and Tips
I do not anticipate that the students will be able to categorize the tissues completely correctly (the connective tissues are especially tricky), hence, the importance of referring back to a textbook at the end of the investigation. I do feel that the discovery process that the students will experience is just as important to their learning of the material.
The observation portion of this investigation can take 1-2 full class days (50 min.) depending on the number of tissue samples you decide to use. The class discussion requires another full day.
Students should have some previous experience in drawing quality representations of specimens under the microscope. If not, take the time to stress the importance of thoughtful, detailed drawings and labels.
If you have a limited number of microscopes, you can use images of tissues from online and project them from your computer for the entire class to draw at once. I prefer allowing the students to be more active and rotate from scope to scope, even if they may have to wait awhile for one to open up.
9-12.IV.B.1 Relate structure of organ systems to function.
9-12.I.A.4 Influence of peer review and consensus on science.