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THE ASSESSMENT OF SIMPLE EXPERIMENT BY
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commonly explained as a complex of reactions in which solar energy is converted into the chemical energy stored in ATP bonds or other organic molecules, namely sugar (glucose). This process is connected with the nutrition of autotrophic organisms but it is very important for all organisms as main source of energy circulating in ecosystems (Reece, Campbell, 2011). It is possible to specify the photosynthesis (and cellular respiration as well) as process which is associated with systems at multiple biological levels from cells to ecosystems and which illustrates transport of energy through biological systems (Akcay, 2017). Moreover the respiration is associated with the photosynthesis immediately.
Only the essential principles of the photosynthesis are appropriate at primary educational level.
Students should understand a conversion of inorganic substances represented by water and carbon dioxide to organic substances such as sugar and the essential role of the light energy as well. They should understand uniqueness of this process and its importance for life. The energy transformations are one of the essentials attributes of the life.
This topic is considered as difficult for teachers and their students (Akcay, 2017). This is accompanied by some additional effects: (1) the problem of choice of a suitable experiment, which is simple, illustrative and well comprehensible for students, (2) is it possible to prepare inquiry lesson(s) and which way, (3) how to asses a students’ work when they design their own experiments oriented on the principles of photosynthesis or respiration.
Research questions:
1) Do pre-service teachers understand basic natural principles? Is it possible to discover it from their products like the design of the experiments?
2) Are pre-service teachers able to design simple experiments aimed on these principles?
3) Do pre-service teachers assess designed experiment as suitable, illustrative, reliable etc.?
METHOD
Pre-service teachers (n = 35) were introduced to the principles of photosynthesis 5 months before start of the research. They designed simple experiment realizable in the classroom, which demonstrate one aspect of the plant physiology – the importance of the light for green plants. Simple drawing in the worksheet was used as a tool for the planning of the experiment.
They used two fields in the worksheet for better readability and easier assessment of final drawing. There was prepared simple drawing of the plant in the boxes. The experimental design was presented by sketches and it was accompanied by information about necessary aids, anticipated results of experiment and some other factors affected plant growth in next three fields.
In the second stage, protocols were assigned randomly to pre-service teachers in the same group for the implementation of the peer assessment process with use of evaluative protocol containing the formative and summative part.
Design (sketch), other answers of respondents and evaluative protocols were coded and analysed with basic statistical methods (frequency, percentage). Afterwards the additional data obtained by the questionnaire were also considered in relation to the results of analysis.
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RESULTS
The role of the light in photosynthesis was explained by the pre-service teachers (respondents) in the first part of worksheet.
Q: “Why the light is needed by plants?”
Relative large group of respondents (26 %) made mistakes or explained it incorrectly or vaguely. In most incorrect cases, respondents took the light for the respiration as necessary.
One respondent considered the oxygen production as main process in the photosynthesis and the light as the essential condition for this. Most incorrect answers laid in an inaccurate formulation within the meaning the light is necessary for plant growth. No answer was referred to basic principles of the photosynthesis, such energy conversion or synthesis of organic substances.
Assessment:
In contrast to this finding all assessors found it as correct explanation (Figure 1). For example assessors did not recognize neutral role of the light in plant respiration. The non-specific answer mentioning the light as condition of life was considered as correct although it do not contain more detailed explanation or reasons. The answers “The light is necessary” or “The light represents one of condition” was found as correct by assessors although it was de facto repetition of the question only. The positive emotional statements were used by all assessors.
Figure 1. The comparison of the explanation of role of the light in photosynthesis stated by respondents (worksheets) and the assessment of assessors (assessment).
Q: “How we can discover that the plants need the light?”
About one half of respondents (49 %) incorrectly defined effect of the light or its deficiency on green plants. For example the flowering or opening/closing of flowers were considered as the phenomenon directly influenced by the light. Some respondents stated the rotation of the flowers or leafs towards the light as the evidence of the light needs not as a result of this. In individual cases respondents connected the light abundance with fruit quality (sweetness) or flower quality (smell), considered visible vaporization (?) as the manifestation of the light
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influence. Many respondents (31 %) considered the growth or stopping of growth as an effect related to the light.
Assessment:
About 83 % of assessors assessed the answers correctly. That means they evaluated correct answers as correct and vice versa. When negative feedback was used, assessor provided information about deficiencies in the answer of respondent.
Q: “Design an experiment which can demonstrate need of the light for green plants. Experiment should be realized in the classroom.”
Respondents used simple sketches for presentation of experimental design. Design of experiment was usually correct when rough draft is assessed. But completely correct design with all required terms was presented in 4 cases only (11 %) (Figure 2). Technical quality of the sketches was not assessed. The assessors focused on the content of picture and its items related to the planned experiment.
Figure 2. Considerable contrast between really correct design of the experiment (worksheets) and the design which was considered by assessors as correct (assessment).
Design of the experiments was very different and varied from incomplete drawings without some necessary details to relative correct drawings with parts which indicate students’ ideas and understanding of the photosynthesis or rather the effect of the light on the plants.
Some sketches represented correct experimental design (Figures 3, 4) and they are representing suitable arrangement but can be incorrect in details. For example flowering or opening/closing of flowers were considered as the phenomenon directly caused by the light. Usually typical can be symbolization of the night or darkness by picture of the Moon (Figure 3). Other sketches contain non-important details on the one hand and crucial items are missed on the other hand (Figure 4).
In several cases, the design/picture included only hint of experimental design. Figure 5 shows experimental design, which represents main idea consisting in comparison of plant lit by the Sun and shaded plant. However, there is not any information about other aids or equipment necessary for the experiment and about condition of the plant.
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Table 1. Other factors (except the light) which were considered as important for plant growth (by respondents).
Feasibility in the classroom
Light source
Correct shading
Flowering Leaves look
Soil or flowerpot
Design clarity
n 34 25 24 12 10 14 23
% 97 71 69 34 29 40 66
Assessment:
The sketches provide opportunity for recognition of understanding the basic principles of plant physiology connected with the light and allow the easier assessment of the experimental design.
But, the assessment is sometimes complicated because it can run into problems with picture quality. At university level, it was not serious problem but demands on skills in reading of the pictures by assessors are important at primary level
Assessors usually considered design as correct but failed to provide feedback in details, e.g.
when necessary aids for plant growing were missing in the experimental design.
In great contrast with number of tiny mistakes, inaccuracies and vagueness most respondents assessed experimental design as fully correct (94 %). Nine assessors provided written feedback with additional information, 8 of them expressed positive emotional statement and only one was negative with recommendation of some improvement of the experimental design.
Figure 3. The example of sketch representing suitable experimental design.
Figure 4. The example of sketch representing experimental design with the emphasis on flowerpot, window and light source but without any indication of light effect on the plant.
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Figure 5. The example representing incomplete sketch without details.
Q: “Necessary aids for the experiment.”
Respondents presented necessary aids for plant growing. Nobody wrote all needed materials and equipment (Table 2). Respondents considered the light source and shading of the plant as most important but other equipment needed for the experiment was mentioned partly.
It seems that respondents understood main principle of experimental design consisting in comparison of two plants grown in different light conditions but they are not sufficiently careful in details.
Table 2. The overview of necessary experimental equipment presented by respondents.
Plant Light source Shading Soil Water Flowerpot
n 22 17 26 3 5 7
% 0.63 0.49 0.74 0.09 0.14 0.20
Assessment:
Assessors stated presented equipment as satisfactory in 89 % of cases. They frequently ignored some missing equipment. In contrast, when they recommended completing equipment, it was in 10 cases only. Usually assessors recommended to complete water, flowerpot and better shading or blackout.
Q: “Other factors influenced plant growth.”
Identification of next factors, which affect plant growing (except the light), showed varied spectrum of statements. Water (in 91 %) and enough of nutrients (in 63 %) were considered as the most important factors. Some respondents mentioned incorrectly relative problematic factors as enough of oxygen, altitude or air etc. (Table 3). This question was not assessed by assessors and inform in fact about knowledge background or problem understanding.
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Table 3. Other factors (except the light) which respondent considered as important for plant growth by respondents.
Factor n % Factor n %
Environment 2 0.06 Cutting 3 0.09
Animals 6 0.17 Season 1 0.03
Human 3 0.09 Gravitation 1 0.03
Saccharides 1 0.03 Altitude 2 0.06
Biome 1 0.03 Species 2 0.06
Oxygen 3 0.09 The elements 1 0.03
DISCUSSION AND CONCLUSIONS
Designing of simply experiments is very important tool for better understanding of principles of life. Above all, it is crucial part of dynamic disciplines like plant physiology and it is often the best way of instruction for understanding some phenomena. It was found that pre-service teachers are able to prepare simple experiment but with (some) misconceptions.
The answers to research questions stated above are following:
1) Preservice teachers do not understand some basic natural principles correctly. Experimental design could be useful as indicator of understanding of problems by pre-service teachers because they have to apply their own theoretical knowledge in concrete problems or situations.
This research supports the assumption that some pre-service teachers work sometimes incorrectly or inaccurately with theoretical knowledge.
2) Especially future primary teachers do not have strong background in science (e.g. biology).
Therefore, designing of simple experiments or labs is necessary component of their preparation (at faculty of education). Most of pre-service teachers are able to prepare simple experiment but they are not careful in details and can have problems with correct explanations what happens during experiment and what is the core of the experiment.
3) Assessment of inquiry is not easy and it is impracticable without deep understanding of basic principles and theoretical background of experiments. It is necessary to develop competence in assessment too. This research shows difficulties in the process of formative assessment, lack of experience with this assessing approach and the need for better background and bigger support for implementation of formative assessment in teacher’s future instruction. This statement corresponds with findings of the research realized in the frame of the project ASSIST-ME (Stuchlikova et al., 2015).