barred spiral galaxy Teacher's Page

Classifying Galaxies: 

A lesson on how Galaxies are classified by shape.

Lesson Plan Content


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The purpose of this lesson is twofold:

1)You will become familiar with the Hubble Tuning Fork Diagram, a system of classification for galaxies invented in the 1920's by the noted astronomer Edwin Hubble. It is still in use today.

2) You will practice the technique, useful in science, of engaging a scheme or plan to classify objects in a group. In this lesson you will be able to look at images of different kinds of galaxies, taken by the world's best telescopes. In most high school astronomy texts and in some earth science texts, the Hubble Tuning Fork Diagram is presented as a way to classify, or put into groups, the various types of galaxies observed in space.

If you are not studying galaxies, this lesson still might be useful. It follows, in an organized way, the process by which scientists group or classify objects in nature. The lesson is designed to be used either way.

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Student Objectives

Students will :

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Teacher Component

Student Component

Students will begin the lesson at the blinking message: "Start your galaxy exploration here". Students will indicate their mastery of the objectives by responding to questions on a paper worksheet.

Lesson Plan Assessment

1. Students will mark their progress by answering questions on a worksheet . This worksheet is provided online for teachers to copy. Teachers may also copy an answer key, also provided online, to check on students' progress.

2. Students will use an ONLINE activity to classify galaxies by placing images of galaxies on the Hubble Tuning Fork diagram, using the classification scheme developed by Edwin Hubble.

3.  Students will examine an unidentified galaxy image, and attempt to classify it based on the methods that they have learned.

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Lesson Plan Ties To Science Framework

Link to Science Standards of Learning for Virginia

Project 2061:    Benchmarks for Science Literacy:    Recommendations of what all students should know and be able to do in science, mathematics, and technology by the time they graduate from high school.

This nationwide study is one of the major frameworks and we include specific references from that study below for grades 5-9:

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Lesson Plan References

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Related Lesson Plans

Hubble Deep Field Academy:  Four activities related to galaxy astronomy:
1- Stellar Statistician: uses the Hubble Deep Field Image in an exercise to teach about sampling.
2- Cosmic Classifiers:  a very visually appealing activity with more complicated galaxy identification involving color, size and shape.
3- Galactic Guide: an activity on determining the distances to galaxies.
4- Universal Graduate: a review quiz on concepts presented in the four lessons above.
Sky Den - an excellent site with basic lessons and multiple links on these topics:
1.Our Solar System
3.Clusters, and Beyond...
5.The Expanding Universe
6.The Big Bang
7.The Fate of Our Universe
8.Weighing the Universe
9.Formation of a Galaxy
10.The Doppler Effect

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This lesson was developed by
George & Jane Hastings 
in collaboration with the
 Science Museum of Virginia

Send comments or questions to George & Jane Hastings or

Copyright 1996, 2001 The Regents of the University of California


This page last updated July 26, 2001