7th Grade Science Labs 2007-2008

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Developing a Classification System for Seeds

Pre Lab Discussion

Suppose you discovered a plant or an animal that no one had ever seen. What would you call it? Where would you even begin?

To simplify the identification and naming of organisms, scientists have developed a system of classification. The classification system groups similar animals, plants and other organisms. There are seven major levels of classification. The broader group is a kingdom. Kingdoms contain phyla (singular phylum), classes, orders, families, genera (singular genus) and species. Organisms of the same species have the most characteristics in common.

In this investigation, you will develop a system of classification for seeds.

  1. Why do scientists classify organisms into groups?

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  1. How is evolution related to classification?

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Problem: What characteristics can be used to classify seeds?

Materials: Container of seeds

Hand lens

Balance

Metric ruler

Paper towel

Procedure:

  1. Pour the seeds onto a paper towel. Use the hand lens to examine the seeds carefully. Answer question 1 in Observations.
  1. Think about what characteristics you could use to divide all the seeds into two large groups. Remember, each group must contain seeds with similar characteristics.
  1. Sort the seeds into two piles, based on the characteristic that you selected. On scrap paper, note the characteristics that you choose.
  1. Working with one of the two large groups, divide the seeds in that group into two smaller groups based on another characteristic. Record the characteristic as in step 3.
  1. Continue to divide the seeds into smaller groups by choosing and recording new characteristics. Eventually, you should have only one type of seed left in each group.
  1. Repeat steps 4 and 5 with the other large group.
  1. As part of your observations draw a flow chart that shows how your classification system works.

Observations:

Flow Chart for Seed Classification

  1. List 4 characteristics of your seeds.
  1. How many groups are in your classification system?

Analysis:

  1. What characteristics did you find most useful for classifying the seeds?
  1. Are your final classification groups different or the same as those of your classmates? Is this expected? Why?

Conclusion:

  1. How does a classification system help you understand organisms?
  1. How is this investigation similar to the way in which scientists classify organisms?
  1. When classifying organisms, is it better to go from general characteristics to specific characteristics or from specific to general characteristics? Give a reason for your answer.
  1. Could you have classified each characteristic in groups of three or more at each step? Do you think more groups would make choices harder or easier? Give a reason for your answer.
  1. Suppose you wanted to classify all the birds that came to a particular area of a pond during a spring day. What are three of the characteristics that you would use to classify the birds?