English and Turkish pupils’ understanding of decomposition

Method

Schools and subjects

To conduct the study regarding seventh grade students’ understanding of ecology, the researcher desired to study with two public schools, one from England and the other from Turkey. One of the comprehensive elementary schools in the Leeds area was chosen for England sample and then, the other elementary schools, from Turkey was selected from one of the public elementary schools in the Marmara region in Turkey.

The sample was a total of 96 seventh grade students had mixed ability with the age ranging from 14-15 years. After permissions were taken from the schools to conduct the study, the researcher did not intervene with their ongoing practices of teaching ecology in both seventh grade classrooms. Seventh grade English and Turkish children learnt similar concepts of decomposition; decomposition of environment, producer, consumer and decomposer relationships in matter and some cycles of materials, food chain and food web, and environmental conservation. All students were taught about those concepts in deep and they had learnt more about the cycles of materials at high school level. At the end of their ecology teaching, the Ecology Test developed by Çetin (1998) was administered to 54 English students from two classes taught by two science teachers from the selected public school in England. Subsequently the Ecology Test was administered to 42 students from two classes taught by one science teacher from the selected school in Turkey. At the same time a questionnaire about the ecology test was given to two teachers in the selected British school and one science teacher in the selected Turkish school.

Although students were expected to have some conceptions might differ from acceptable scientific views on ecology, it was assumed that the level of the questions in the Ecology Test was appropriate for the seventh grade students; therefore each student was considered having the capacity to answer the questions in measuring. However, a student's ability to answer the questions successfully depended upon the student's previous knowledge, skills, and experience (Germann & Aram, 1996). The Ecology Test was administered following the same instructions given by the researcher in both selected schools in England and in Turkey. All students answered the questions in the Ecology Test seriously and sincerely. However, the sample of the study was limited to 96 seventh grade students at the public elementary school in Turkey and the public elementary school in England in the Spring Semester of 1997-1998. This study was also limited to the Ecology concepts in the Turkish science curricula and the English science curricula in seventh grade level.

Data Collection

Students' levels of understanding of decomposition were determined by four diagnostic questions related to some concepts of decomposition. Those questions were selected from an Ecology Test developed by Çetin (1998). Figure 1 shows four test items regarding decomposition involved two multiple-choice questions required reasoning and two open-ended questions related to some basic concepts of decomposition from seventh grade English and Turkish science curricula. Question 1-3 assessed the students' understanding of decomposition of organic molecules, decomposition in environment, producer, consumer, and decomposer relationships in the cycle of materials. Question 4 examined how the students realized the decomposition of biodegradable materials and non-biodegradable materials, and environmental conservation.

To construct the Ecology Test, a concept map of ecology related to food chain, food web, and decomposition was drawn. The test items were designed to assess students' ability to interpret and apply some ecological concepts. The researcher was aware of the fact that many Turkish questions in elementary school exam papers only assessed recalled knowledge. All questions in the Ecology Test were modified versions of some of the questions obtained from Key Stage 3 level exam papers as well as English science textbooks, and Ph.D. thesis about ecology (Leach, 1995). The test was phrased in English and later translated to the Turkish Language. Much care was taken to ensure that the level of language used was suitable for the Turkish students and some Turkish colleagues evaluated the suitability of the language used. Two biology educators; one British and one Turkish performed the content validation of the items. Finally, the Ecology Test included some multiple-choice questions required justifying each response made, and open-ended items required short answers. The data were collected from the English students first and then, they were collected from the Turkish students by post. All students were told the test was not an achievement test, but not to copy one another's work during the test. The test duration was one hour.

Additionally, a questionnaire involving six items was administered to one British and one Turkish science teacher to determine which of the selected concepts taught in class, and to obtain their opinions of the level of difficulty of test items. It also aimed to elicit methods used by the teachers to determine the students' understanding of the ecological concepts and lastly the problems that students might face during the test administration.

Data analyses

The aim of the study was to explicate the ideas of the English and Turkish students concerning decomposition, not to compare their achievements of decomposition. In order to attain the students' opinions about ecology, the students were expected to choose one alternative from four alternatives given in the multiple-choice question, and then to explain why they made that choice in brief given blank space in the Ecology Test. In open-ended question the students were expected to express their ideas about the question in short given blank space in the Ecology Test. Here the students' responses/explanations to four questions regarding decomposition were scored and coded as like other questions in the Ecology Test.

Question 1. Complex organic molecules are broken down and recycled in an ecosystem. Carbon dioxide and mineral ions are made available for re-use.

a) Which one of the following is mainly responsible for breaking down complex molecules in an ecosystem?

A producers

B consumers

C micro-organisms

D soil

b) Explain your answer briefly.

Question 2. This diagram below represents a part of the carbon cycle.

a) How is carbon compounds released from plants after death?

A decay

B evaporation

C photosynthesis

D reproduction

b) Explain why you made that choice.

Question 3. John put four apples in a glass bowl, but then he forgot to eat them for two weeks. He noticed that they have a bad smell and have lost their original shape.

Explain briefly why they can smell and lost their original shape.

Question 4. Although some rubbish can be decomposed (broken down) in a short time some cannot.

This table below shows how long some rubbish takes to decompose.

Cigarette ends……… 1 to 5 years

Orange peels…… … ..2 years

Plastic bags……… … 10 to 20 years

Tin cans…………… .50 years

Nylon fabrics……… 30 to 40 years

Explain why orange peel is broken down in 2 years but tin cans can take 50 years to break down.

Figure 1: Question 1-4 Related to the Concepts of Decomposition

A test paper of each student was numbered from 1 to 96 and then, the students' responses to each question in the Ecology Test were scored between 0-3. If a student responded to the multiple-choice part correctly and provided an explanation with sound understanding, the score “3” was given to the student. If a student responded to the multiple-choice part correctly and provided an explanation with partial understanding, the score “2” was given to the student. When a student responded to the multiple-choice part correctly and provided an explanation with misunderstanding, then the score “1” was given. When a student responded to the multiple-choice part wrongly, the score “0” was given without accounting for the response provided in the second part. If a student gave no response to both parts for the item asked, then the score “0” was used.

In addition, students' ideas obtained from the students' responses to the test items were identified and classified according to a coding scheme generated by the researcher (Keng, 1997; Simpson & Marek, 1988). A student's response to each question could involve more than one idea, so a student's idea as a part of the response was chosen as the unit of analysis. Each student's idea was collected from their explanations in the reasoning parts of multiple-choice and open-ended questions in the Ecology Test. These ideas were listed in order and similar ideas for each question were linked together. An extended list of ideas in response to each question was generated in mutually exclusive categories as much as possible.

At the beginning of scoring and content analysis of the students' responses to the questions, acceptable scientific explanations were written for each question in the test by the researcher as a guide. Two experts; one English biology educator and one Turkish biology educator validated these scientific explanations. This guide formed the basis of the codes and the categorization process for the student's ideas extracted from the students' responses to each question. One English biology educator, one Turkish biology educator, and one English physics educator reviewed the codes and assigned categories for students' ideas according to their levels of understanding of decomposition. Necessary revisions were done accordingly until reaching an agreement. In this manner, the coding schemes were developed, and an initial coding was executed and experts validated those coded ideas before conducting an exhaustive coding of the students' ideas.

Finally students' ideas related to decomposition were classified under four categories: Sound understanding (SU), partial understanding (PU), misunderstanding (MU), and no understanding (NU). SU meant if the students' responses included the scientifically acceptable explanations about the questions, they were considered having sound understanding. PU meant if the students' responses were partly correct and did not include the scientifically acceptable explanations about the questions, they were considered having partial understanding. MU meant if the students' responses did not include acceptable explanations, it implied that the students had some misinterpretations or misjudgments about the questions. Some responses of the students were grouped as misunderstandings if they were clearly different from the scientific view. NU meant if the students could not make proper explanation(s) from the scientific point of view or restate questions for the multiple-choice questions and the open-ended questions, they were considered to have no understanding at all. In short, this broad category contained rewrite responses that restated the questions, non-sense or irrelevant responses that could not be coded meaningfully, and no response where the space was left empty or with the response, “I don't know”. Table I-IV displays students' levels of understanding and percentages of response categories for the questions.