Beacon Lesson Plan Library

Physical Difference and Classification

Carol Houck

Description

The students compare and contrast several physical properties and develop a classification system using observation skills and a microscope.

Objectives

The student identifies various ways in which substances differ (e.g., mass, volume, shape, density, texture, and reaction to temperature and light).

The student knows that a change in one or more variables may alter the outcome of an investigation.

Materials

-Each group should have a tray of materials that includes:
- 1 nail
- 1 rubber band
- 1 rubber ball
- 5 cm copper wire
- 25 ml water
- 25 g ice
- 1 small mirror or other object with a reflective surface
- 1 magnet
- 5 g cornstarch
- 5 g lead ball
- 5 g salt
- 1 microscope

For the class: one timer or clock

Preparations

A discussion of physical properties and classification may be necessary prior to this activity.

Individual trays should be prepared before beginning this activity. Each tray should contain items that possess different types of physical properties that uniquely distinguishes them from other items by at least one characteristic. For example: A nail that is magnetic, a rubber band that stretches, a rubber ball that bounces, a piece of wire that is ductile (i.e., easily molded), water that is a liquid, an ice cube that is a cold solid, a mirror that reflects an image, a magnet that attracts metal, a very dense lead ball, a powder as cornstarch, salt crystals. Other items may be substituted.

A discussion of proper microscope usage may be necessary.

Procedures

1. Organize students into groups of four. Instruct students to follow all lab safety rules.
2. Have students prepare a table with four columns. In column one, students will list the items on the tray. A unique characteristic of each item will be listed in column two. Microscopic physical properties will be listed in column three. A comparison of the physical properties of an unknown item to the items listed in column two will be placed in column four. Have students label the columns as follows: one, item; two, physical property; three, microscopic physical property; four, compare and contrast.

Part One: Observable Physical Characteristics
3. Instruct students to list the names of the items on their trays in column one.
4. Tell students they will have five minutes to determine one special physical property for each item on the tray. The items will have many characteristics, but each item should have one property that is unique. The unique physical properties will be listed in column two.
5. Allow students to begin the activity. At the end of five minutes, call time.
6. Allow groups to compare answers. Discuss all possible answers and allow students to change their results based on the class discussion.

Part Two: Microscopic Properties
7. Tell students they will have 10 minutes to determine one special microscopic physical property possessed by each item on the tray. The items will have many characteristics, but each item should have one property that is unique. The unique microscopic physical properties will be listed in column three.
8. Allow students to examine each item under the microscope to determine its unique microscopic physical property. Call time at the end of 10 minutes.
9. Allow groups to compare answers. Discuss all possible answers, and allow students to change their results based on the class discussion.

Part Three: Classify an Unknown Item
10. Distribute an item not found on the tray to each group; for example, a piece of string or gelatin. Each group must receive a piece of the same new item.
11. Instruct each group to determine which unique physical characteristics from column two are also unique to the new item. Instruct students to place a check (3) in column four for each unique physical property also exhibited by the new item. The new item may exhibit more than one unique physical property listed in column two.
12. Instruct each group to place the new item under the microscope and observe its microscopic physical properties.
13. Have students determine which unique microscopic physical characteristics from column three are also unique to the new item. Instruct students to place an -x- in column four for each unique microscopic physical property also exhibited by the new item. The new item may exhibit more than one unique microscopic physical property listed in column three.
14. Allow students to classify the new item based on their observations. For example, students may determine that the new item has observable physical properties of a ball and of a rubber band. Students may also determine that the new item has microscopic properties of a nail. Therefore, the new item may be classified as ball, rubber band, and nail.
15. Discuss results with the class. Arrive at consensus on one classification for the new item.
16. Direct students to answer the following questions.
a. Which physical properties are easiest to observe? Which are the most difficult?
b. Which microscopic properties are the easiest to observe? Which are the most difficult?
c. Which observable physical properties were also exhibited by the new item?
d. Which microscopic properties were also exhibited by the new item?
e. How did you classify the new item?
f. After the discussion, did you agree with your classification or should the new item be classified differently or listed separately on your table? Why or why not?
g. Is it possible to classify all materials in the room using your table?
h. What other tests might you perform to help you classify all materials?
i. What other physical properties have not been listed on your table?
j. What other microscopic physical properties have not been listed on your table?
k. What ways do scientists use to classify materials? Provide some examples.

Assessments

Assessment questions may include:

1. Which of the following physical characteristics may be observed without the aid of a microscope?
a. atomic structure
b. crystal shape
c. color
d. molecular size

(answer c: Color may be observed without the aid of a microscope.)

2. Which of the following characteristics would be best observed using a microscope?
a. crystal shape
b. color
c. density
d. odor

(answer a: Crystal shape may be best observed using a microscope.)

3. Which of the properties listed below may be used to classify materials?
a. crystal shape
b. color
c. density
d. all of the above

(answer d: Materials may be classified using each or all of these properties.)

4. What purpose does a microscope serve in making observations?
a. determines an object's weight
b. helps measure an object's density
c. helps observe small characteristics
d. helps determine an object's color

(answer c: A microscope helps observe small characteristics.)

Cooperative learning skills may be assessed using the Cooperative Group Rubric (see associated file).


Self-Reflection:
How can you use your skills of observation in your daily life? In what situations might you have to be more observant? What other tools do you use every day to help you make observations?

Extensions

Self-Reflection:
How can you use your skills of observation in your daily life? In what situations might you have to be more observant? What other tools do you use every day to help you make observations?

Invite a forensic expert to make a presentation to the class. The expert could discuss training needed, skills needed, and tools used by the investigators.

The teacher could stage a fake crime. A stranger could walk in the classroom unannounced, take something the teacher is using and run out. The students would be challenged to write down as many details about the intruder as they remember from the short observation. Students could share and compare observations. Then the intruder could return and reenact the 'crime' exactly as before. Students should check off correct observations as well as note how many details they missed in their observation.

Attached Files

A cooperative group rubric.     File Extension: pdf

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