Sea Urchin Embryology Back to Contents page

 

 

 

| OVERHEADS | GLOSSARY | REFERENCES | SKILLS | CLASSIC |

DRAWING LESSON

SUMMARY: This lesson concentrates on two aspects of using drawings to illustrate and record observations:

1. Minimalist or "cartoon" drawings to just illustrate the points being made without distracting information
2. Detailed drawings to show as much information as possible

EASY

| TIMING | BACKGROUND | MATERIALS | PROCEDURE | MATH | IMPLICATIONS | EVALUATION |

TIMING

45-50 minute class period

BACKGROUND:

You do not need to be a Leonardo to draw, but you do need to learn how to SEE. And in SEEING, we learn much more about the subject of interest.

MATERIALS

The overhead consists of a matched set of four subjects, with a line drawing representation on the left and a photographic image on the right. All of these images are taken from our sea urchin lab.

You can easily substitute your own! Make sure the line drawing does not match exactly the photograph. Remind students that they are to draw what they SEE, not what they think the drawing should look like.

overhead images include:

sperm line drawing

scanning electron microscope image of a sperm

egg line drawing

light microscope image

eight cell stage embryo drawing

scanning electron microscope image of an embryo

pluteus embryo drawing

light microscope image

 PROCEDURE

  1. Have students fold a piece of white paper into quarters. This will give them a total of 8 areas in which to draw.
  2. Proceed through the 8 figures, discussing the changes and the points to look for. NOTE: Have the students label the right hand drawing the same way as on the left (That is, can they recognize in the photograph the same structures labeled in the drawing)
  3. The line drawing represents how LITTLE detail one needs to illustrate the main points. The photograph is used to practice showing as much detail as possible, without obscuring the essential information.
  4. Have the students write about what they have done. Why did they choose to show some information and not other? Were there "tricks" that aided quick completion? Did they like doing the assignment? Did it help knowing what the subject was, or was it better to just draw what you saw?
  5. As a warm up exercise, have students do a new figure for the first five minutes of class several times a week.

NOTE: the drawings do not match the images exactly! Example: the egg line drawing is of an unfertilized cell, but the image is a 60-minute embryo. Seeing, means seeing the differences also!

MATH

Look carefully at proportions in your drawings. Are the width and length the correct proportion? Is the size of the mitochondria in correct proportion to the rest of the sperm? Are the individual cells in the 8 cell embryo the same size? What about the length of the arms in the pluteus, are they the same length or different?

IMPLICATIONS

  1. What is the importance of accurate drawings? Show your drawing to someone else in the class. Can they identify what parts accurately without the labels you have added?
  2. Why do scientific journals prefer the use of photographs over drawings?
  3. Does your answer to #2 change when you add in what can now be done with digital imagery?

EVALUATION

 TIP: A good way to practice drawing skills early in the year is to introduce brine shrimp as a "newly discovered life form". Students are to pretend that they have never seen these organisms and that they are recording the details of their body structure to share with scientists for the very first time. Ask students to record details of size, proportion, anatomical structures, numbers of appendages and then to scientifically name their organism based on observed features. (A dollar's worth at the local pet store will provide ample material for ALL of your classes.)

Estimated class time:

Day 1 general observations and drawings 45-50 minutes class period

Day 2 close-up drawings, behavior studies, binomial nomenclature 45-50 minute class period