Making Observations and Formulating a Dichotomous Key

FORMULATING A DICHOTOMOUS KEY

1. Make a list of observations for each of the four leaves.

2. Using the observations, formulate a dichotomous key to identify four leaf types. There should be one less step than the total number of organisms to be identified in your dichotomous key. ANSWER KEY FOR FORMULATING A DICHOTOMOUS KEY

1. Make a list of observations for each of the four leaves.

2. Using the observations, formulate a dichotomous key to identify four leaf types. (A Sample)

1. Needle-like leaves...... Spruce

1. Broad leaves...... 2.

2. Parallel veins...... Corn

2. Net veins...... 3.

3. Simple leaf...... Oak

3. Compound leaf...... Horse Chestnut FORMULATING A DICHOTOMOUS KEY

Four insects: a housefly, a grasshopper, a ladybug and a dragonfly.

 Start by observing the group of things to be used in the key.  List the most general traits that can be used to divide the organisms into categories.  Now, use your characteristics to fill in the Dichotomous Key below

Notice that there were four organisms to be identified and it only takes three steps. There should be one less step than the total number of organisms to be identified in your dichotomous key. ANSWER KEY FOR FORMULATING A DICHOTOMOUS KEY

Four insects: a housefly, a grasshopper, a ladybug and a dragonfly.

 Start by observing the group of things to be used in the key.  List the most general traits that can be used to divide the organisms into categories.  Now, use your characteristics to fill in the Dichotomous Key below

A SAMPLE KEY

1. Large muscular legs for hopping ………………………………… Grasshopper

1. Small legs – 3 pair about the same size ………………………… go to 2

2. Outer pair of wings for a hard covering for the body ………………. Lady bug

2. Wing membranous …………………………………………………… go to 3

3. One pair of wings …………………………………………………….. Fly

3. Two pair of wings …………………………………………………… Dragonfly

Notice that there were four organisms to be identified and it only takes three steps. There should be one less step than the total number of organisms to be identified in your dichotomous key.