The effects of Swedish Knife Model on students’ understanding of the digestive system

The Results of the Test Items

The tables present the average DST scores at pre-test and post-test: the percentages of students’ answers, in terms of digestion and the digestive tract, are shown in Table 3.

**Table 3.** Percentages of students’ answers about the digestion and digestive tract
Categories	Pre-test (N=40)	Post-test (N=40)
Test Item 1 CE	17,5	20
PC	75	80
CW	0	0
W	5	0
UE/NE	2,5	0
Test Item 2a CE	47,5	35
PC	10	20
CW	32,5	27,5
W	0	0
UE/NE	10	17,5
Test Item 2b CE	42,5	85
PC	30	7,5
CW	27,5	7,5
W	0	0
UE/NE	0	0

When the pre-test findings of the first question, regarding the definition of digestion were evaluated, it was ascertained that 75% of the students stated partial definitions of digestion, such as ‘nutrients become as small as fitting into the cell membrane’ or ‘nutrients are broken into pieces by enzymes’, without expressing anything about mechanical or chemical digestion. In the post-test, the ratio of students' partial explanations increased 80%. The ratio of the CE increased 20% from 17,5%. In the first part of the second question, it was asked where digestion starts and finishes. As seen in Table 3, in the pre-test, 47,5% of the students gave correct answers, 32,5% of them had some misconceptions and 10% of them did not answer the question. The answers which were categorized under CW included that ‘digestion finishes in the large intestine or it finishes in the anus’. In the post-test, these ratios changed as 35%, 27,5% and 17,5% respectively. When the findings of the second part of the test (regarding digestive system organs and structures) were evaluated, it was ascertained that the ratio of CE was 42,5% in the pre-test and that this had increased to 85% in the post-test. In the pre-test, 30% of the students gave partial explanations, without including the terms ‘esophagus’ and ‘large intestine’. This ratio decreased 7,5% in the post-test. 27,5% of the students made CW explanations, stating that the ‘pancreas, liver and kidney are also parts of the digestive tract’. Some of the students wrote the large intestine before the small intestine. In the post-test, this ratio decreased by 7,5%. In the third and fourth questions of the test, it was asked in which organs chemical and mechanical digestion occurs and the reasons for their answers. The percentages of the students’ answers were given in the Table 4.

**Table 4.** Percentages of students’ answers about the mechanic and chemical digestion
Categories	Pre-test (N=40)	Post-test (N=40)
Test Item 3a CE	60	75
PC	20	15
CW	20	7,5
W	0	0
UE/NE	0	2,5
Test Item 3b CE	40	55
PC	22,5	15
CW	2,5	0
W	12,5	17,5
UE/NE	22,5	12,5
Test Item 4a CE	22,5	27,5
PC	17,5	10
CW	47,5	27,5
W	7,5	12,5
UE/NE	5	22,5
Test Item 4b CE	15	32,5
PC	7,5	12,5
CW	35	30
W	27,5	2,5
UE/NE	15	22,5

The pre-test findings of the third question, in which the chemical digestion occurring in organs was evaluated, it was found that 60% of the students had answered correctly, 20% of them had partially answered the question and 20% of them had misconceptions. In the post-test, these ratios changed as 75%, 15% and 7,5% respectively. Students’ CW answers showed that they believed that “foods are digested chemically in the large intestine or liver or esophagus”. The students expressed that ‘food was broken into pieces chemically by the liquid/acid secreted by these organs’ and they did not use the concept of ‘enzyme’. The ratios of the answers, regarding the reasons for their answers, were 40% CE; 22,5%, PC; 2,5%, CW, 12,5% W and 22,5% NE. In the post-test, these ratios changed as 55%, 15%, 0%, 17,5% and 12,5% respectively. When Table 4 was evaluated, it was seen that 47,5% of the students had misconceptions. Most of these students wrote mouth and stomach but they also added “esophagus” or “liver” or “small” or “large intestines” to their answers. In the post-test, these ratios were increased to 27,5%. On the other hand 7,5% of the students stated that “mechanical digestion occurs in the liver or large intestine or pharynx” and this ratio increased by 12,5% in the post test. Some of the students expressed how ‘mechanical digestion occurs in these organs, as there is no enzyme in these organs’. Other students stated that ‘mechanical digestion occurs in these organs, in order to facilitate chemical digestion’. The fifth and sixth questions of the test respectively asked about the functions of the liver and the large intestine in digestion. Table 5 represents the data related with fifth and sixth questions.

**Table 5.** Percentages of students’ answers about liver and large intestine
Categories	Pre-test (N=40)	Post-test (N=40)
Test Item 5 CE	27,5	10
PC	12,5	10
CW	40	40
W	7,5	15
UE/NE	12,5	25
Test Item 6 CE	15	37,5
PC	25	35
CW	30	12,5
W	22,5	12,5
UE/NE	7,5	2,5

40% of the students had misconceptions about the liver and 7,5% gave wrong answers, stating that ‘the liver digests fats mechanically’. In the post-test, the ratio of misconceptions equal to 40% and the ratio of wrong answers increased to 15%. As it can be seen in the table, 30% of students had misconceptions about the large intestine and 22,5% of them gave wrong answers, using statements such as ’the large intestine digests foods’ and ’it excrete wastes from the body’. In the post-test, it was revealed that the ratio of correct answers increased 37,5%; while the ratios of wrong answers decreased 12,5%. All the misconceptions held by the sample in the pre and post-tests were given totally in the Table 6.

**Table 6.** Misconceptions of the students in the pre and pos-test
No	Misconceptions	Pre-test	Post-test
No	Misconceptions	F	F
1	Digestion is absorption of nutrient we swallowed by the organs	1	0
	Digestion is breaking nutrient into small pieces by grinding	1	0
	Digestion is separating needs from the wastes by breaking nutrient into small pieces	1	0
2a	Digestion begins in the mouth and ends in large intestine	4	4
	Digestion begins in the mouth and ends in anus	3	0
	Digestion begins in stomach and end in small intestine	1	0
3a	There is chemical digestion in small intestine because nutrients are absorbed here	1	0
4a	Nutrients are not digested mechanically in pharynx and esophagus because there is no enzyme in here	1	0
	Liver	1	0
	Large intestine Large intestine and pharynx Esophagus and large intestine	1 1 1	1 0 0
	Fats are digested mechanically in small intestine	7	14
5	Liver turns toxic substance into bile	1	0
	Liver digests fats mechanically	8	4
	Pancreas secretes bile	1	0
	Liver facilitates the absorption of nutrients into the small intestine by the aid of bile	2	0
	Liver digests food chemically	2	0
6	Large intestine excretes the wastes from the body	1	0
	Water expels nutrient wastes and urea from the body	2	0
	Large intestine digests minerals and nutrient Large intestine makes chemical and mechanical digestion	2 2	0 0
	Large intestine transmits wastes to kidneys	3	0
	Large intestine save some of the fats in small intestine	1	1

As seen in the Tables, the majority of these misconceptions were remedied after the treatment.

The Results of the Students’ Analogies

Students developed analogies for the mouth, esophagus, stomach and the small and large intestines and the frequencies of their analogies were set out in the Table 7. Some of the students didn’t write analogy for some organs because of that frequency of some organs are not equal to sample number.

Table 7. The frequencies of students’ analogies
Target Concept	Analog	f	Similarity
Mouth	grinder grater blender mixer electric saw washing machine	26 4 4 3 1 2	disintegrate disintegrate disintegrate disintegrate disintegrate mixing
Esophagus	water pipe pump sink pipe snake elevator	30 2 4 1 2	transmission pumping transmission shape transmission
Stomach	mixer bag- store blender food processor harbor leaven making machine	25 4 4 1 1 2	mixing and splitting storage blending disintegrate storage and transmission mixing
Small intestine	pipe road rope radiator dishwashing sponge bus roots of tree sink	14 11 4 2 2 2 1 2	transmission transmission thin and long transmission absorption transmission shape elimination of waste
Large intestine	sponge waste box trash compactor pipe road sewer pipe water treatment plant car harbor	9 8 6 5 2 3 2 1 2	absorption containing waste digestion transmission long elimination of waste elimination of waste transmission transmission

As seen in Table 7, students developed simple analogies, in accordance with one or two characteristics of the digestive organ/structure. Most of the students made functional analogies for mouth. Students likened the mouth to a grinder or a blender or a mixer or a grater. Students made functional and physical analogies for esophagus. They mostly likened the esophagus to a water or sink pipe. The analogies for the stomach were mixer, bag-store and blender due to its function of ‘mixing’. The small intestine was likened to a pipe, a road or a rope because of its shape and function. Two of the students likened it to a sink by putting large intestine. Same problems were present for the large intestine. Students confused the functions of large and small intestine.

Findings of Students’ Interviews

The students were interviewed about the effectiveness of the instructional process. They were asked about their teachers’ teaching methods. The answer of the students indicated that the teachers were mostly using traditional teaching methods. Student 1 indicated that:

Our teacher tells us and then asks questions to detect what we learned. After finishing the lesson, we answer the question in our student workbook. We had a human model; he shows the organs on it.

Student 2 from other class aid that:

Our teacher mostly tells us. But sometime we watch film related with the subject and make drama.

Students were also asked to assess the teaching process and the activities. All the students indicated that the teaching process was very enjoyable as a whole. They also stated that they learnt much more during the process. Some of the statements of the students as follow:

…we enjoyed very much, all the activities were interesting and exciting. For example, finding poems, organs and analogs was very interesting. We have not been taught like this. It was new for us (ST3)

The lessons were very active and interesting. We were active during the teaching process. We prefer to learn other subjects with this kinds of activities (ST5).

Students indicated that the cut-and-stick activity supported their learning of organs and their connection with each others. They also stated that the activities increased their motivation and attitudes to science.