Part III. Neutrino oscillations
Theme 4 CD4): Kinetic Energy
Q4. An object moving at a constant velocity v has a kinetic energy E. The velocity is changed to 2 v. Which ONE of the following is the correct kinetic energy at this velocity?
A. ¼ E B. ½ E C. 2 E
D. 4 E (2)
Learners’ comments:
“Because the velocity is constant when it is changed to 2 v, the kinetic energy is doubled”. [Chose option D – which was the intended response].
“It is because the kinetic energy is halved for that velocity that changes from the E that was 2 v to ½ E”. [Chose option B].
“Because the kinetic energy increases by velocity squared if there is any increase in velocity:
“E = ½ mv2 = ½ m 2 v2 = ½ m 4 v2 E = 2 E
Therefore, the kinetic energy is 2 E”. [Chose option C].
“2 E – the work done + kinetic energy leads to the movement of an object to be 2 E kinetic energy”. [Chose option C].
“Kinetic energy is inversely proportional to the velocity of an object therefore when the velocity doubles itself, the kinetic energy will be halved therefore it would be ½ E.”.
[Chose option B].
“As the velocity changes to 2v, so the kinetic energy will be 2E”. [Chose option C].
Most learners did not correctly relate the changes in velocity to kinetic energy. The popular response was that if the velocity is changed from v to 2v, kinetic energy also would be changed from E to 2E. They were unable to square the velocity in the kinetic energy equation and hence the majority option was C (2E) which suggested that doubling the velocity of an object, would also lead to the doubling of the kinetic energy – which is not the case.
The above two conceptual difficulties appear to come from the kinetic energy concept in that learners could not square the velocity in the kinetic energy formula to solve the problem. As in question 3, by doubling the velocity, the kinetic energy becomes fourfold the previous one.
Theme 5 (CD5): Application of the Principle of Conservation of Mechanical Energy {Q13. Nthabiseng, a cyclist, is free-wheeling (moving without peddling) along a horizontal surface at a constant speed of 10 m.s-1. She reaches the bottom of a ramp (position A) that has a height of 1,2 m and a length of 8 m. While free-wheeling up the ramp, she experiences a frictional force of 18 N. The total mass of the cyclist is 55 kg.
Which ONE of the following best describes her situation?
A. Her mechanical energy is conserved.
B. Her mechanical energy is not conserved.
C. Her potential energy is conserved.
D. Her mechanical energy is constant.}
In this question, learners could not identify key words like ‘she experiences a frictional force of 18N’, and hence the majority of learners applied the Principle of Conservation of Mechanical energy which made them to make wrong choices.
Learners’ comments on Question13:
“The law of conservation of mechanical energy was applied”. [Chose option A].
“I am not quite sure of my answer”. [Chose option A].
“The energy changes when it is not sloppy”. [Chose option D].
Overall, learners did not appear to understand the Principle of Conservation of Mechanical Energy, and failed to consider that mechanical energy is only conserved if there are no external forces or non-conservative forces, like frictional force acting on the system. The Principle is about a closed system and this excludes external forces. The intended response was option B.
Development of Instructional Interventions
Following the identification of conceptual difficulties experienced by the respondents, three sets of instructional interventions were developed with a view to overcoming these difficulties, namely, ‘traditional’, ‘outcome based education’ (OBE) and ‘blended’. The traditional teaching / learning strategy was selected on the basis that reception learning (Ausubel 1962, 1963 & 1977) still remains the dominant teaching and learning strategy in many South African schools and, according to Coetzee (2008), could alleviate students’
learning difficulties and alternative conceptions – if implemented effectively. OBE was selected as one of the intervention instructional strategies for this study on the basis that it forms the main approach recommended for the implementation of South Africa’s National Curriculum Statement (Department of Basic Education 2012). The blended instructional strategy was selected because of its use of multiple approaches, as a way of accommodating the many learning styles that students bring to the classroom (Ellis, Steed
& Applebee 2006; Ocak 2011; Pape 2010; Cronjé 2011). By way of definition, Ellis, et.al (2006: 313) opine that blended learning is a “systematic combinations of e-learning and face to face learning.”
Once these three instructional strategies had been identified, instructional materials for the respective approaches were then developed. In this regard the ‘traditional’ intervention, treated concepts in a teacher-centred learning modality – typical of reception learning, whereby the teacher stands at the front of the classroom and the students passively sit at their desks and listen to the teacher. The lecturing or telling method, and the exclusive use of the prescribed textbook, typified this instructional approach. Accordingly, within class
time, very little or no interaction and communication amongst students, and between the students and the teacher, took place, although the teacher occasionally made use of questions to check students’ attention and understanding.
For the OBE group concepts were treated based on the constructivist way of teaching and learning. Learners’ questions, comments, responses in tests and during class formed an important part of classroom interactions. Based on the constructivist educational principles, OBE entails an open interaction between the educator and the learners, as well as learner- learner interactions. Thus, the constructivist approach focused on quality over quantity (Mintzes, et al, 1998:327). Gray (1987) also posits that constructivism uses a process approach, focusing on the ideas which are allowed to develop in the learner’s own mind through a series of activities. According to the constructivist view, for learners to develop an understanding of the conventional concepts and principles of science, more is required than simply providing practical experiences. More guidance is needed to help learners assimilate their practical experiences into what is possibly a new way of thinking about them (Driver, 1983). A variety of instructional methods were used during this intervention, and these entailed use of interactive student-centred methods. Learners’ questions, comments, responses on tests and work at the chalk board were used. Learners’ answers were probed to identify the reasons behind these answers. The students were encouraged to actively participate, as much as possible, in the programme through the use of written assignments, giving timely feedback to students, controlled class discussions, negotiating meaning in practical work and small group discussions, hands-on activities, individual problem solving tasks, articulating relevant personal experiences, and wrestling with real world problems rather than memorising answers. Thus, the teacher played the role of a facilitator, ascertaining what the learners already knew, and organize instruction that built on that knowledge. Application of real-life situations was central, and individuality was accommodated as far as possible. The variety of instructional methods compensated for student diversity. Understanding was assessed by means of different continuous assessment assignments – including peer and self-assessment. Furthermore, students were encouraged to use other sources in addition to the prescribed textbook, e.g. reference lists of similar textbooks in the library, lecture material, notes, internet, consultations with other physical science educators and other educators and peers.
In blended learning, concepts and principles are treated in modalities that mix various event-based activities: self-paced learning, live e-learning and face-to-face classrooms. An efficient blended learning programme includes a mixture of these three learning types (Alonso, Lopez, Manrique & Vines, 2005). According to Alonso, et.al, (2005), blended learning combines training, coaching, and self-help. In blended learning, teaching and learning involve face-to-face classroom interactions (traditional way of teaching), open interactions between the educator and the learners, interactions among learners themselves, computer-mediated teaching and learning, and co-operative learning. A continuum of teaching strategies was used in the clarification of mechanics concepts and principles.
Thus, in summarizing the interventions, it may be said that the traditional approach to teaching and learning is mainly dominated by lecture or telling method and memorization by learners. The teacher is the disseminator of information. For its part, the OBE approach is dominated by group discussions and the educator is regarded as the facilitator of learning. With regard to the blended approach, all teaching strategies and methods are vitally important since learners tend to have different learner characteristics, with different learning styles. As facilitator, the teacher chooses instructional strategies in the most appropriate and relevant combinations.
Activity Theory as the Theoretical Model for Implementing the Instructional Interventions
The main elements of the Activity Theory (AT) are summarized in Figure 2.
Figure 2. Activity System (based on Engestrom, 1987) for three intervention groups (traditional, OBE and blended)
According to Figure 2, an Activity System consists of mediating tools, subject, object, goal or outcome, division of labour, community and rules. Thus, regarding the traditional intervention, the teacher remained in complete control of the class. He was also a disseminator of information; classroom proceedings were teacher-centred; there was little or no interaction among the learners; and, occasionally, the teacher made use of questions to check learners’ attention.
According to this model, the “subject” comprised a group of 35 grade 12 physical science learners. The main object was to identify the conceptual difficulties held by these students in mechanics. The expected outcome was the alleviation of the students’ conceptual difficulties in mechanics. The subject and the object were mediated by prescribed textbooks, assignments, worksheets and the TBM (used as both pre- and post-test) as the tools for the traditional intervention. The teacher and the group of thirty five (35) students formed the community as they were sharing the same object with the subject. With regard to the division of labour, the teacher prepared worksheets, TBM, provided input and feedback to learners. Learners were expected to understand the information presented to them, completed worksheets and wrote the TBM. Learners had to follow the rules as outlined in the TBM, worksheets and also to be silent while the test or lessons were in progress.
Regarding the OBE intervention, the teacher served as a facilitator of learning; classroom proceedings were learner-centred, and there were interactions among the learners and between the learners and the teacher – who sometimes made use of questions to check
Subject Object
Mediating Tools
Object
Outcome
Rules
Community Divisionof Labour