Activity One: Red and Yellow Squares, Triangles, and Circles
Each of you has been given 12 pieces of paper.
Divide the papers into two groups. What characteristic did you use to divide them?
Put your papers back into one group. Divide them into three. What were the three characteristics used to separate them?
Put your papers back into one group. Divide them into six groups. What are the characteristics used to separate them?
If you would make a graph for the data it might look like the following:
_____ _____ _____ _____ _____ _____ ................_____ _____ _____ _____ _____ _____
Write the name of each unique object at the end of the path that identifies it.
You identified 12 objects. Another way to represent this is with a dichotomous key.
Below is a dichotomous key for this set of objects. It divides the objects into pairs, the first pair is red and yellow (1A and 1B). Depending on the color of the object to identify the next number is chosen from the one that describes the object (2 or 7). Continue the procedure until the object is identified.
Use a large red circle and follow it on the key:
1 A Red paper (2) 1B Yellow paper (7) 2A Circle (3) 2B Non circle (4) 3A Large red circle 3B Small red circle 4A Square (5) 4B Triangle (6) 5A Large red square 5B Small red square 6A Large red triangle 6B Small red triangle 7A Circle (8) 7B Non circle (9) 8A Large yellow circle 8B Small yellow circle 9A Square (10) 9B Triangle (11) 10A Large yellow square 10B Small yellow square 11A Large yellow triangle 11B Small yellow triangle
Note that when something is "keyed down", it is identified. It has been classified completely when you reach the boldface print.
Try to identify several pieces of paper on the key, such as a small yellow triangle, until you know how to use it easily.
Activity Two: What's the Object
In a small container are a number of objects which can be graphed the same way as the bits of colored paper. Fill in the graph below:
The objects can also be identified with a dichotomous key. Have a partner select one object from the container, without you seeing what it is, and ask your partner questions to identify the object.
1A Object made of metal (2) 1B Object not made of metal (5)
2A Shaft mostly smooth (3)
2B Shaft with deep grooves on it) (4)
3A TWO INCHES OR LONGER NAIL
3B LESS THAN TWO INCHES BRAD OR TACK 4A + ON TOP PHILLIPS SCREW 4B ONE SLIT ON TOP SCREW 5A Match (6) 5B Toothpick (7) 6A WOODEN SHAFT WOODEN MATCH 6B PAPER SHAFT PAPER MATCH
7A ROUND SHAFT, POINTED AT BOTH ENDS ROUND TOOTHPICK
7B FLAT SHAFT, POINTED and ROUNDED on each END. FLAT TOOTHPICK
Now key out a paper match.
Keys are useful in the identification of plants and animals. Your teacher can give you keys to identify: deciduous trees, evergreen trees, insects or other objects.
Activity Three: Making Your Own Key
To really understand a key you should make one for yourself. Try one for animals like: pigeon, rattlesnake, rabbit, goldfish, earthworm and butterfly.
First, you might want to record the similarities and differences of the animals in a chart.
After you have collected enough data you can make a graph. Here is one started for you.
or a chart might help:
pigeon rattlesnake rabbit goldfish worm butterfly wings scales feathers warm blooded cold blooded backbone fur live totally under water
Now complete the dichotomous key:
1A Animals without a backbone (2)
1B Animals with a backbone
2A With legs - BUTTERFLY 2B Without legs - 3A 3B 4A 4B 5A 5B 6A 6B 7A 7B
Now that you understand how to make a graph or a dichotomous key you can use them to help sort, classify, or identify objects.
See examples - leaf identification chart leaf identification chart
Dr. Robert Sweetland's Notes ©