How Do Scientists Do Science

Senior Form Chemistry
– How do scientists do science? /

How do scientists do science?

Teacher’s Version (with video exemplars)

NOS/STSE Features
1. Scientists publish their work. The quality of the publications is often safeguarded by peer review.
2. Peer review aims to be objective but social or personal values may sometimes affect scientific judgement.
3. Scientists should not submit to authority.
4. Experimental and non-experimental studies are both valuable in science.
5. All cultures can contribute to science.
6. Collaboration is common in science.
7. Both females and males can contribute to science.
8. Most scientific research is multi-disciplinary.
You can click an icon like this to access the activities in this package.
You can click an icon like this to access the PowerPoint files in this package.
You can click an icon like this to access the exemplar videos in this package.

Table of Contents

Introduction / (i)
Activity 1: How do scientists tell other scientists what they are doing? / P.1
Activity 2: Is vitamin C a cure for colds? / P.8
Activity 3: Are experiments the only way to develop scientific knowledge? / P.11
Extension activity: Investigations about vitamin C / P.14
Appendix 1: A list of papers for the extension activity / P.18
Appendix 2: Lesson Plan / P.19

Senior Form Chemistry
– How do scientists do science? /

Introduction

Rationale

“How is scientific knowledge established?” is a question not addressed by many science textbooks. In this set of materials, students have the chance to experience the process of reviewing and evaluating scientific papers. How scientists solve some problems in research will be investigated by looking into some studies on vitamin C.

This package also emphasizes the value of non-experimental research in science. Students will be able to analyze the benefits and drawbacks of experimental and non-experimental approaches to research. This will broaden their scope when they design scientific investigations.

Level of study Number of lessons

Form 6 4 lessons (each lesson 35-40 minutes)

Contents

1. Peer review among scientists

2. Evaluating scientific study

3. The use of experimental and non-experimental approaches to investigation in science

4. Myths about science and scientists

Teaching package includes

1. Worksheets (Teacher’s Version and Student’s Version)

2. A Teaching PowerPoint

Senior Form Chemistry
– How do scientists do science? /
Activity 1
How do scientists tell other scientists what they are doing?

Notes: The PowerPoint contains a more detailed description of Linus Pauling. Teacher may ask students to discover more about the life of Linus Pauling.

Q1 Was Linus Pauling a chemist or a biologist?

He was both a chemist and a biochemist. (He worked across disciplines.)

Homework (Optional): Look for more information about Linus Pauling! Why was Pauling given the Nobel Peace Prize in 1962? What does this tell you about the participation of scientists in society?

Scientists also participate actively in society. They may join social campaigns or be active in affecting political decisions.

Reference:

Nobel Prize official website: http://nobelprize.org/ (Last visited: 1/6/2006)

Biography of Linus Pauling: http://nobelprize.org/peace/laureates/1962/pauling-bio.html (Last visited: 1/6/2006) (English version only)

Look at the cartoon showing the conversation between two scientists and discuss the questions with your classmates.

Q1 Why do scientists have to spend time searching out and reading other scientists’ work?

They can avoid repeating the work that was done by other scientists.
They can base their own ideas on the work of others and also develop others’ work.

Q2 Why have scientists conducted so many studies about the effects of vitamin C rather than simply believing in what Pauling said?

Although Pauling was a renowned figure, his idea was not consistent with what other scientists had shown. People might not believe that vitamin C can treat the common cold.
In order that Pauling’s idea may be accepted, extensive investigations have to be conducted to demonstrate the effectiveness of vitamin C.

Notes: Students will take the role of scientists / journal reviewers to evaluate the quality of scientific papers in next part.

As stated in the cartoon, scientists have to publish their work in print or on the internet, in “scientific journals” to let other scientists know about their results. There are thousands of scientific journals in the world. You can find some in the public libraries.

When a scientist submits a study to a particular journal the work will be reviewed by the editorial board. The board is composed of a group of scientists. They will review the quality of the papers and determine whether the papers are good enough to be published.

Additional information: In an editorial board, there is a chief editor who will receive manuscripts from scientists. The board meets to decide which manuscripts might be suitable for publication. Then each one is sent to a number of reviewers for further comment before making a final decision.

The job of a reviewer (who is an expert in the field of the study) is to evaluate the quality of a scientific paper. Factors such as (i) the significance and originality of the research (ii) the validity of the investigation (iii) the trustworthiness of the results and findings (iv) the quality of the writing and overall presentation will be considered. A significant piece of research may open up new directions or areas for further investigation. A reviewer will not repeat the research to check reliability. They will use their professional knowledge to judge whether the paper is worthy of publication.

Notes: The reading of the manuscripts can be assigned as homework while the discussion should take place in the class. This activity is also suitable for Form 6 students for report writing. Instead of using the manuscripts given, students may comment on their own reports.

Remarks: Students are expected to experience the review process with emphasis on the nature of science:

1. The fame of the institution might bias the process of review (Therefore, in the activity, the names and institutions of the authors are removed before the review process.)

2. Conflict of interest of reviewers (Reviewer 4 in this activity) might bias their decision. But the peer review system tries to minimize this effect and guards fairness.

Let’s try the reviewing process! Divide into groups of four. Each of you will be a reviewer of the Journal of Nutrition. Choose your role first!

Remarks: The papers are on p.7 and 8.

Reviewer 1 (Dr. Kelvin King)

You are Dr. Kelvin King, a senior scientist at The China Nutrition Institute, also a reviewer for the Journal of Nutrition. You have just received two papers from the chief editor. Every journal has limited space. You have to decide which paper can be published in the journal. You may also reject both papers.

Reviewer 2 (Dr. Louise Lee)

You are Dr. Louise Lee, a senior scientist at The University of Hong Kong, and a reviewer for the Journal of Nutrition. You have just received two papers from the chief editor. Every journal has limited space. You have to decide which paper can be published in the journal. You may also reject both papers.

Reviewer 3 (Dr. Mary Wong)

You are Dr. Mary Wong, a senior scientist at England University, also a reviewer for the Journal of Nutrition. You have just received two papers from the chief editor. Every journal has limited space. You have to decide which paper can be published in the journal. You may also reject both papers.

Reviewer 4 (Dr. John Talaka)

You are Dr. John Talaka, a senior scientist at The University of Paris, also a reviewer for the Journal of Nutrition. You have just received two papers from the chief editor. Every journal has limited space. You have to decide which paper can be published in the journal. You may also reject both papers.

After you have received the papers, you find that the study is very similar to the research that you have been doing. You are also about to publish your results. If you allow the paper you are reviewing to be published before yours, the impact of your study will become less significant. In the science community, those who publish new finding will gain more credit.

Justify your decision in the following boxes.

Manuscript 1
Accept / reject (Please circle your decision)
Reasons:
Manuscript 2
Accept / reject (Please circle your decision)
Reasons:

Vote for the papers! Which paper did your group accept, or did your group reject both? Now summarize the reasons for the group’s decision and present them to classmates.

A comparison of the manuscripts:

Manuscript 1 (M1) / Manuscript 2 (M2) / Comment
Materials and methods / 1g of vit C powder is dissolved in 200ml water / 1g of vit C powder is dissolved in 500ml water / The differences are unlikely to affect the result.
20oC, 40 oC… / 25oC, 40 oC…
Solutions were kept at constant temperature for 30 minutes.R / Solutions were kept at constant temperature for 15 minutes. / The effect of heating on vitamin C might be better shown by M1.
Experiment was repeated until consistent results were obtained. R / Experiment was done in triplicate. / The method in M1 ensured more reliable results.
Results and discussion / No description on the use of statistical analysis program. / It described the program used in statistical analysis. / More details were given in M2. But the difference in the choice of statistical program might not affect the results. (It is the method of analysis which might affect the results.)
Summary / It stated that food processing would not affect vitamin C content. / It described other factors that may affect the stability of vitamin C. R / The summary of M1 was not supported by its results. For M2, it opened new areas for further studies.

Remarks: Teachers may develop the consequences of rejection further if students seem interested.

Manuscript 1

Vitamin C is not destroyed by heat

Notes: Name of authors and institutes are removed for the review process.

Introduction

Vitamin C is believed to be lost during cooking. People always believed that we could not take in enough vitamin C from cooked food. The purpose of the study is to investigate whether heat can destroy vitamin C.

Materials and Methods

Vitamin C powder was purchased from ChemTech Ltd. A solution was prepared by dissolving 1 g of powder into 200 ml distilled water. 10 ml of vitamin C solution was kept at 20℃, 40℃, 60℃ , 80℃ or 100℃ for 30 minutes. The vitamin C content was then measured by titrating the vitamin C solution against 1 ml DCPIP solution. The experiment was repeated until consistent results were obtained.

Results and Discussion

The results are illustrated in the diagram below. There was no significant difference in vitamin C content remaining after treatment at different temperatures.

Summary

The results indicated that heat did not destroy vitamin C. Thus, food processing will not affect the vitamin C content of a particular food.

Manuscript 2

Vitamin C Destruction during Heating

Notes: Name of authors and institutes are removed for the review process.

Introduction

Vitamin C is a vital substance for health. Heating is believed to destroy vitamin C thus lowering the vitamin C content in food during cooking. The purpose of this experiment was to determine whether increasing temperatures decompose Vitamin C.

Materials and Methods

Vitamin C solution was obtained by dissolving 1g of vitamin C in 500 ml distilled water (vitamin C tablets were purchased from BioChem Technology Ltd.). For each temperature, 50 ml of vitamin C solution was used. The solutions were heated to 40℃, 60℃ 80℃ or 100℃ and maintained at a constant temperature for 15 minutes. A control solution was maintained at room temperature (25℃).

After 15 minutes, vitamin C concentration was measured by titrating the vitamin C solution against 1 ml DCPIP solution. The amount of vitamin C solution used was recorded. The procedure was repeated three times at each temperature.

Results and Discussion

The correlation between temperature and vitamin C concentration was determined using the Statistical Analysis Computer Program version 1.0. There was no significant difference in vitamin C content at different temperatures. The results are shown in fig.1.

Summary

Vitamin C is not destroyed by heating. This is especially important for the food processing industries. However, other factors such as oxidation and the decomposition of vitamin C in different solutions (e.g. salt solution), which have not been considered in this study, may also affect the availability of this micronutrient to consumers. Further study is needed.

Activity 2
Is vitamin C a cure for colds?

Unlike humans, most mammals are able to synthesize their own vitamin C. They are able to produce vitamin C from glucose in the following steps:

Most of the above biochemical pathway also happens in our body. However, our body does not have Enzyme Z. As a result, when glucose has been converted to chemical C, the reaction stops and humans cannot synthesize vitamin C. We need it from our diet.

It has been found that when some animals are sick, the amount of vitamin C in their body will increase tremendously. Therefore, Linus Pauling suggested that the missing enzyme is due to a genetic deficiency in our evolution and that when we are sick, we would, like other mammals, need more vitamin C.

Pauling caused controversy about using vitamin C for treating or preventing disease. His hypothesis is not easy to prove or disprove, but he has triggered extensive research on the use of vitamin C for the treatment of colds. This famous experiment was conducted by Karlowski and his colleagues in 1975. Details are on the next page:

Remarks: This is the pathway by which glucose is converted to ascorbic acid in mammals.

Source: Le Couteur, P. & Burreson, J. (2003) Napoleon's buttons: how 17 molecules changed history. New York: J.P. Tarcher/Putnam, pp.46-47

Notes: Teachers might like to ask students to devise a plan to test the hypotheses.

Notes: Vitamin C tablets and lactose (glucose can be used instead of lactose) must be given to students to taste. This can guide students to answer the questions on the next page.