Summer Research Program for Science Teachers

Carlos Franco

Manhattan Center for Science and Mathematics

2002

Which brand of Air Freshener is most cost effective?

Objectives:

Having worked in a research lab this past summer, I got an opportunity to understand the how scientists do science. I learned four very important practices that I am integrating into my classes this year. (1) Scientists do not follow “cook book” labs to investigate tasks that confront them daily. Even though there are certain protocols for certain procedures, scientists must be able to devise experimental designs and modify standard protocols to solve problems or tests hypotheses. (2) Results from an investigation do not arise overnight. In other words, scientists sometimes must wait long periods of time to obtain results (Standard D: Structure the time available so that students are able to engage in extended investigations). Unfortunately, students usually carry out investigations in which results are obtained in an unrealistic period of time: at the end of a class period. (3) Scientists do not work in isolation they work in groups. (4) Scientists have a sense of the connection between their research and the real world.

Description:

Based on these four concepts, I devised the scientific activity presented in this portfolio entry. Students were presented with a problem: which air freshener is the most cost effective. They had to integrate their understanding of phase changes and properties of matter, which was a large component discussed in a three-week unit titled matter and energy, mathematics, and their experiences as consumers (Standard B: encourage and model the skills of scientific inquiry). Like scientists, students had to come up with a method, devise an experimental design by identifying dependent and independent variables, and work in groups of four or five. In addition, this investigation would take two weeks to obtain enough data to determine the most cost-effective air freshener.

By carrying out this investigation students, would use the scientific method to determine the most cost-effective air freshener. In addition, they would communicate with each other as they developed their strategy to attack the problem, but most importantly, they would take the principles they learned about matter and their mathematics skills to solve a problem that is relevant to the real world. In other words, students must be able to see that what they learn in the classroom is applicable to the real world, and once students can make that connection science becomes real to them. Not all of my students will become scientists but I want them to leave my class knowing that the concepts and skills they learned in chemistry are true problem-solving skills.

Materials:

Depending on the methods student devise to answer the question will determine the materials they will need; however, the following materials students usually request to carry out this investigation.

Several brands of air fresheners (students purchased)

Triple-beam balance

Metric rulers

Development:

As mentioned before this activity usually takes about three weeks to complete; however only two forty minute periods are required: one period to aide students in developing their approach to answering the problem and one period for students to present their data to the class. Data collections is carried out throughout the three weeks in short periods: one may assigned ten minute periods for data collection twice a week before or after school/ class.

Session I: Students develop their approach to solving the problem

Time duration: 60 minutes

Goals:

ØStudents will develop hypothesis (Standard B: Focus and support inquiries while interacting with students)

ØStudents will design investigation (Standard D: Structure the time available so that students are able to engage in extended investigations)

ØStudents will confer in working groups

ØStudents will develop tentative data sheet

This lesson is primarily inquiry base; one needs to develop a series of questions that will initiate student interest. The following are some of the lessons that I developed:

(Standard D: Engage students in designing the learning environment.)

Q. What is meant by cost effectiveness?

Q. Why is it important to determine the cost effectiveness of a product?

Q. How would a study on the cost effectiveness of a product help society?

Q. What are air fresheners? Why do people purchase them? How do they work? (Develop a series of questions that will help you in assessing class knowledge of air fresheners.)

Q. Of all the brands of air freshener in the market, which one would you consider the most effective the cheapest brand or the most expensive brand.

Q. How would you test your hypothesis? What materials would you need?

I recommend that you carry out this activity in groups of three or four students (standard B: Recognize and respond to student diversity and encourage all students to participate fully in science learning). Thus, each group must confer and decide how they will test their hypothesis. They must develop their data sheets and inform you of the materials they will need to carryout the investigations. Finally, each group must inform you when they will collect their data.

Between the first and second session you must allocate time for data collections as well as poster/PowerPoint preparation. Usually there is a two-week lapse between the first and second session.

Session II: Students present their data via poster boards or PowerPoint presentations

Time duration: 60 minutes

Goals:

ØStudents will communicate their findings orally to the rest of the class

ØStudents will assessed by their peers on their approach and conclusions (Standard C: Guide students in self-assessment)

During this session each group speaks for five minutes on their findings and an extra two minutes is allocates for questions/ answers. At the end of each presentation, each group submits a lab report on their investigation. The lab report allows you to assess further the degree of understanding the students acquire throughout this experience (Standard C: Analyze assessment data to guide teaching)

Laboratory Report Format

Your lab reports will be composed of the following parts:

III.      Introduction                                                                               15 points

Explain the purpose and goals of the investigation. Furthermore, explain what skills and concepts acquired this year in chemistry did you apply to carryout your investigation. Secondly, state your problem or hypothesis (please underline). Finally, what significance does this investigation have to the “real’ world.

Note: Try to be creative in this section; the introduction is what captures your reader’s attention.

IV.      Methods                                                                                       5 points

Explain how you carried out your investigation. You want to write it in such a way that anyone could replicate your investigation ( DO NOT WRITE IN THE FIRST PERSON- avoid I, WE, etc. )

V.        Results                                                                                         5 points

In this section you want to present your data in a table or a graph. When you present your data make sure you indicate appropriate units and any formulas that you used

VI.      Discussion                                                                                    10 points

In this section you discuss (1) how your data answered your problem or supported/ rejected your hypothesis; (2) what patterns in the data surprised you and why; and (3) comment on what others who have done similar projects have concluded.

VII.     Conclusion                                                                                   15 points

Discuss what future investigations you would like to carryout based on your experiences/results in this investigation. That is, what would you do different and why

Due date: ___________________