Millar, Marechal and Tiberghien (1998) define practical work in science teaching as teaching and learning activities which engage students in handling or observing real object or materials that can enhance learning. Similarly, Maselwa and Ngcoza (2003) explain practical activities as 'hands-on’, 'm inds-on’ and 'w ords-on’ learning tasks. Likewise, M illar (2004) refers to a practical activity as any teaching and learning activity which at some point integrates the learners in observing or manipulating the objects and other resources they are studying.
Teaching o f science thus requires practical activities to prove the scientific theories and enhance learners’ participation in the learning o f content. It is due to that, that Hodson (1990) stresses that practical work can serve as a vehicle for arousal o f learners’ interest and curiosity. In the same vein, Parkinson (2002, p.114) states that “learners enjoy practical work and that they learn through seeing things happen” .
According to M illar (2004, p.20), “practical work is an essential component o f science teaching and learning, both for the aim of developing students scientific knowledge about science” . In addition to that, practical activities enable learners become exposed to manipulating apparatus and thus acquire manipulative and observation skills (ibid). Millar (2004) continues to explain that practical work can take place in the laboratory as experimental work, but it can also take place without laboratory equipment. Roberts (2004) classified practical activities into five different categories that include skills practical, observation, technological, investigations and exploratory tasks. Through practical activities learners would be able to create a link between practical work and observed scientific process as it is supported by M illar (2010, p.2) who commends that “practical work helps students to develop their understanding o f science, appreciate that science is based on evidence and acquire hands-on skills that are essential if students are to progress in science” . It means that, experiments can be used as a supporting evidence to confirm the presence o f certain chemicals(s) in a substance(s). It is for these reasons that science is regarded as a reality o f nature that can be confirmed through scientific experiment.
It is accentuated that as learners do experiments, ideas are modified and refined and so are shaped towards a shared set that makes discourse and collaborative action possible (Millar, 2004). It could be argued that practical activities may avoid rote memorization in learners because they make learners remember better when engaged in practical work.
Practical work enables learners to develop skills including improvising o f apparatus to be used, handling o f tools, observation, measuring, recording data and writing up the conclusions. Mukwambo (2012, p. 36) expresses that “some properties o f practical work are; it is a medium o f communicating ideas and can be achieved graphically, pictorially or symbolically” . Practical activity has a social constructivist’s character as it allows learners to interact with each other while the teacher is facilitating the session. Furthermore, it emerged from M ukwambo’s (2012) study that the science ideas emerged from the experiment are discussed by learners in concepts map and mind maps in establishing science evidence they would have found.
It is expressed that practical activities can bring changes in helping learners to know the environment and other natural phenomenon through learning and teaching discourses (Millar, 2004). In the same line o f thought, Mukwambo (2012) stressed that learners develop scientific habits o f mind as they use practical activities which are the tools o f scientific enquiry. They ask questions and analysis of information and in this way it would lead to them to engage in those habits o f mind mentioned.
Maselwa and Ngcoza (2003) confirm that practical work encourages learners at various stages of inquiry to predict explain, explore, observe and explain (PEEOE) particularly when learners have freedom to direct and adapt the activities according to the questions which emerge from their own experiences. This means that the PEEOE approach could help learners to develop scientific concepts o f a specific topic so as to make sense o f science in general. It is thus suggested that learning science should involve seeing, handling and manipulating real objects and materials and that teaching science will involve the act o f showing as well as o f telling.
Woodley (2009, p.50) indicates that “when done well, practical work can stimulate and engage students learning at different level, challenging them mentally and physically in ways that others science experiences cannot” . Science is a practical subject that requires learners to use their hands and minds to draw the conclusion based on concepts, projects or problems to be solved.
Ramsden (1994) states that for curiosity to be aroused and stimulated, there is a need for the teacher to position activities and experiments in the context o f everyday life experiences o f learners. Hence, the practical work enquires learners’ prior experiences (ibid). Apart from that, Oloruntegbe and Ikpe (2011) express that if learners do not see science as a real-life experience, they are likely to experience difficulty and challenge in learning science and become disenchanted with studying it. Thus, practical activities can motivate learners to develop the sense o f ownership o f the science subject.
It was advised that when approaching the end o f any activity, teachers should facilitate the process whereby learners design their own representation o f the underlying concepts o f the experiment that can be done in simple way such as 'm ind m aps’ and 'concepts m aps’ (Maselwa & Ngcoza, 2003). Similarly, Zion and Slezak (2005) claim that the role o f a teacher during practical activities is to display flexibility, innovation as well as allocating time to the learners and encourage them to be proactive in the activities.
Pea (1993) states that if the aims o f the practical work are precisely and clearly stated to the learners in a conducive learning environment, practical works can attract learners’ attention to learn better. Similarly, Woodley (2009, p.50) illustrates that in “planning an activity, the task should be tailored to achieve the identified aims, for example through discussion between students” . In addition to that Woodley (2009) further indicated that proper planning may improve the effectiveness o f practical activities to meet particular aims. In the same light o f though, M illar (2010) outlines that the starting point o f a designed practical activity is the learning objectives that the teacher had in mind, and it is what the students are intended to learn from the activity.
According to Woodley (2009, p.49), “most practitioners would agree that good-quality practical work can engage students help them to develop important skills, help them to understand the process o f scientific investigation and develop their understanding of concepts” . In addition, Woodley (2009) further states that really effective practical activities enable learners to construct a bridge between what they can see and handle (hands-on) and scientific ideas that account for their observations (brains-on).
W hen learners design a model or carry out scientific projects or investigations may help them to improve their cognitive and creative skills. Other importance o f practical activities in science teaching as expressed by M illar (2010) are:
• To encourage accurate observation and description; • To arouse and maintain interest;
• To make phenomena more real; and
• To promote a logical and reasoning method o f though.
Hodson (1990) further claims that practical activities improve acquisition o f laboratory skills; therefore teachers must focus on skills which allow learners to be engaged in useful activities. Despite all the above mentioned uses o f practical activities during teaching and learning in science classrooms, there are however, have some weaknesses.
In this study practical activities were applied through ASEI lesson interventions. Hence, in the next section I discuss ASEI-PDSI as a teaching approach in which practical activities are being integrated.