Inductive Activities

The inductive approach provides students with a learning situation in which they can discover a concept or principle. This is, in a sense, an "experience before vocabulary."

In this activity, a traditional lab activity is redesigned into a constructivists approach type activity. The 5 E Instructional Model (developed by BSCS, 1990) was followed.

Title of activity

 

When It Pours - It Flows

Engagement

Capture the students' attention. In this case, a question was asked. The discussion is designed to guide students to make connections between what they know and what they are about to study.

 

Questions asked to students

 

Do all liquids pour at the same rate? If not, why not?

 

During the discussion of the question, the teacher focuses on key concepts that students will need to know in order to move to the next stage. Equipment is later demonstrated to lead the student into developing an investigation activity. Such equipment as graduated cylinder, glass bead, and stop watch will be presented.

Exploration

Students carry out investigation to gather information, test out ideas, record observations, etc.

Students are asked to design an experiment to measure the relative rates of flow of various liquids.

How can we devise a method to compare the rate of flow of various liquids?

 

Small groups are formed

Students are divided into small groups of three to four students.

Roles are given to each member of the group:

1) materials person - this person will get all materials

2) recorder - this person will write down any activity design and will prepare a chart for data entry

3) information seeker - this is the only person who will be permitted to ask the teacher a question. All questions must be asked in such a way to permit a "yes" or "no" response

4) coordinator - this person is to make sure that all members of the group do their job and to monitor the time

Each group is given 5 liquid samples (water, mineral oil, kerosene, motor oil, household lubricating oil) in a capped culture tube. Each tube contains a glass bead. The time needed for the bead to fall from top to bottom with the capped tube can be measured. This data can be used to place the liquids by their relative viscosity.

Students are to design an activity to rank various liquids by their ability to flow - from fastest flow to slowest.

Possible data chart - try to let students develop their own charts - however, list the material names and the number of carbon atoms per molecule.

Material	Carbon Atoms Per Molecule	Average Time For Bead To Fall	Relative Viscosity
mineral oil	12-20
kerosene	12-16
motor oil	15-18
water	NA
household oil	14-18

Explanation

Students are to make sense from their exploration. They are to find patterns and relationships and answers to questions. Students are urged to explain their findings and to demonstrate their understanding.

This is where the term viscosity is introduced: Viscosity - is the term for resistance to flow. A material with high viscosity flows slowly and with difficulty.

Develop a table to place your data of relative viscosity. Include in this table average time data for the bead to fall.

Students are to place their data on large sheets of paper - which will later be taped to the board.

Students are asked what other factors may influence the viscosity of a liquid. Hot water baths are provided for exploration.

Elaboration

Students are given opportunities to apply the concepts and skills that they have acquired to different situations.

Lubricating oil is used in automobile engines. In order for oil to flow through the many small openings in an engine, the oil must have a low viscosity. However, too low of a viscosity will prevent proper lubrication. Therefore, it is important to have oil of a viscosity adjusted for various factors.

 

Questions

What may occur in an engine that will affect oil viscosity?

How might engine oil differ in the winter compared to the summer?

Why do you believe that most engine oils today are multi-viscosity?

Evaluation

Call upon students to demonstrate their knowledge and understanding of the ideas under study.

As a group, answer these questions.

• Propose a rule, based on your observations, about the connection between the number of carbon atoms in a molecule and its viscosity.

• Is it possible for petroleum fractions to be separated at room temperature on the basis of their viscosities? Explain your answer.

 

What would be some advantages of such a separation procedure?

As a group, respond to the following statement. In your response, use terms such as viscosity, large chain molecules, hot and cold temperature, and evaporation.

 

Gasoline and geography

When shipping gasoline and motor oils to different parts of the nation, petroleum distributors must consider both the ease of evaporation and viscosity of these products. Why must gasoline shipped to a northern state (such as Minnesota) in winter be different from that shipped to a southern state ( such as Florida) in summer?

Present your response to the class. Each group gives a 1-2 minute presentation.