A number of different instructional models have been developed that can help teachers organize and sequence investigative learning experiences for their learners. By means of a model. the features of a scientific investigation may be combined in a series of coherent learning experiences that help learners build new understandings and develop their
investigative skills over time (NRC, 2000). They also provide opportunities for learners to extend, apply, and evaluate what they have learned (Bybee, 1997).
2.4.1 The RNCS model
Implicit in the RNCS (Department of Education, 2002b) for Natural Science is a model which sequences the investigation process into stages. The following stages have been identified, planning investigations; conducting investigations and collecting data; and
evaluating data and communicating findings. This model implies a linear approach to investigation, where there is a starting-point at which the investigation question is
formulated and an end-point at which the findings of the investigation are communicated.
This model if applied rigidly, suggests limited learning experiences as there is no opportunity for the learners to apply and extend what they have learned. For this reason other types involving cyclic types are recommended.
2.4.2 Wellington's model
Wellington states that "in an ideal world, however, a model of investigational work should follow a cyclic approach" (2000, p. 162). The following model by Wellington (2000, p.
162) explains this cyclic approach.
Ask questions, make plans, predict and hypothesize
Analyze and interpret results, evaluate scientific evidence
Observe, measure and manipulate
variables
Figure 2.1 A cyclic view of investigational work Note: From "Teaching and learning secondary science" (p. 162), by
Wellington, 2000, London: Routledge
From this model it is seen that the process of interpreting and evaluating results is not necessarily an end-point. Instead, it leads back to the first activity of asking new questions, making revised plans and revisiting predictions.
2.4.3 Llewellyn's model
A similar model referred to as an inquiry cycle is described by Llewellyn (2002, p. 15).
The model comprising of six cyclic phases is shown in Figure 2.2. This model is similar to Wellington's model, however it is more descriptive and detailed in identifying six phases in the inquiry cycle. In this cycle, the phases of the inquiry are sequentially arranged from the acquisition phase through to the exhibition phase. Following the inquiry cycle, learners
often enter and re-enter the phases at different aspects of their inquiry process. Thus, the inquiry cycle serves as a model to guide learners through their inquiries and investigations (Llewellyn, 2002).
This description of an investigation in terms of the inquiry cycle is compatible with the definition of a "full inquiry" as presented by the NRC (1996) of the United States in the National Science Education Standards. This document defines "full inquiry" as a process in which students (a) pose a productive question; (b) design an investigation directed towards answering that question; (c) carry-out the investigation, gathering the applicable data in the process; (d) interpret and document their findings; and (e) publish or present their findings in an open forum.
2. Acquisition:
"Brainstorming"
possible solutions
3. Supposition:
selecting a statement to test
I. Inquisition:
Stating a question to
be investigated
6. Exhibition:
Sharing and
communicating results
A
5. Summation: collecting evidence
and drawing conclusions
4. Implementation:
Designing and carrying out a plan
Figure 2.2 The inquiry cycle
Note: From "Inquire within" (p. 15) by D. Llewellyn, 2002, Thousand Oaks, CA: Corwin Press.
2.4.4 The APU model
In addition to the inquiry cycle described above, a further iterative model (Figure 2.3) is used by the Assessment of Performance Unit (APU) (as cited in Watson, 1994, p. 28).
V
Interpreting data And drawing conclusions
IV
Recording data -tables
-graphs
According to this model, the starting point in the investigation process is to find out from the learners what the problem is, what they think the problem is about, and so is concerned with the learner's perception of the problem and its reformulation into a form which can be investigated. The iterative part is concerned with changing one's mind in the light of fresh evidence and going back to an earlier stage to reformulate the problem or change the plan.
la
Problem - generation - perception
lb
Reformulation -into form open to
investigation -deciding what to
measure
Further Solution
formulation
VI
Evaluation of
Change in -results
design - method
11
Planning an experiment -setting up conditions
Ill
Carrying out the experiment -using apparatus
-making measurements -making observations
Change in technique
Figure 2.3 The APU model of an investigation
Note: From "Students' engagement in practical problem solving- (p. 28), International Journal of Science Education, 16(1), 27-43 by J.R. Watson, 1994.
2.4.5 Commentary
The criticism leveled at instructional models for investigations is similar as that which applies to models in general. That is, they simplify the world. Teachers and others can be misled into thinking of them as "lockstep, prescriptive devices — rather than as general guides for designing instruction that help learning to unfold through inquiry, which must always be adapted to the needs of particular learners, the specific learning goals, and the
context of learning" (NRC, 2000, p. 35). In developing a suitable model for investigation
"the aim must therefore be to develop a general model of 'investigational work' which learners can use and apply in a number of different situations" (Wellington, 2000, p. 162).
The need is for a flexible model that provides guidance for learners and teachers who are comfortable with more autonomy and open-endedness. as well as for learners and teachers who have little previous inquiry experience and need more guidance (Songer, Lee &
McDonald, 2003). One of the foci of the current study was to develop such a model which could assist teachers in the implementation of scientific investigations as described in the RNCS (Department of Education, 2002b) in South Africa.