Challenges of Concept-Based Approach: Assessing Learning Outcomes

Assessments have their place in studying the effectiveness of instructional strategies. Gauging the effectiveness of teaching and learning in the concept-based approach involves more than just exams and course evaluations. Assessments have to be formative in nature, and they need to help the learner modify their thought processes in light of the ongoing concept acquisition. The formative assessments should also provide information for making course corrections leading to more effective teaching and learning. For example, if the teacher notices that some students do not understand a lesson, he/she can stop and review or ask the students to discuss what is not being understood. The teacher uses that information to modify the lecture or class activity based on student input. The difficulty, especially in higher education, is the lecture is interrupted, and material covered decreased.

Nevertheless, it must be pointed out here that there is no benefit in covering more material when students do not understand what is being said. DiCarlo points out the greater challenge would be the mindset of educators themselves who are apprehensive about making the change and question “What about content mastery?” (2006). It is better to cover less, work for deeper understanding of fundamental concepts and promote long-term fusing of new ideas onto the student’s conceptual framework. In addition, the time spent helping students to reason through an issue develops their intellectual processing skills so that they will become better independent learners and achieve long-term retention of concepts and skills. To enhance the students’ learning, the teacher could at the beginning of a topic use a pretest in order to determine the current level of understanding achieved by all students. Doing so can also

Table 1 Conceptual questions

Heat is given off when methane bums in air according to the equation:

CH4 + O2 ^ CO2 + 2H2O

Which of the following is responsible for the heat being given off?

(a) Breaking carbon, hydrogen and oxygen bonds gives off energy

(b) Forming carbon-oxygen and hydrogen-oxygen bonds gives off energy

(c) Both breaking and forming bonds give off energy

provide an opportunity for opening the classroom dialogue leading to increased communication and learning.

However, a bigger challenge in assessing learning in the concept-based approach is to come up with the appropriate performance tasks which can effectively assess the students’ understanding of the concepts while allowing the students to demonstrate their acquisition and organisational schema of disciplinary knowledge in the topic. Furthermore, the choice of skills to be tested will also determine the type of performance task being set. Performance tasks are also difficult to carry out because they are quite resource dependent. In this respect, educators have since trialled ways of using summative assessments to address this challenge. Concept-based examinations, both in structured response formats (usually multiple-choice type) and unstructured response formats (usually short answer or free response), are being used as effective tools in assessing students’ conceptual learning and understanding as well as the level of chemistry misconceptions they hold.

Therefore, it has been suggested that the use of a list of questions that draw attention to core concepts, such as the Chemical Concepts Inventory (CCI) (Mulford, 1996), can be used to check student’s misconceptions. Hence, a common question that students taking A-level Chemistry courses encounter is the topic of combustion, and they often learn that the heat produced during burning is due to bond breaking and bond formation. The point of a conceptual focus in the questions therefore comes by way of offering three distinct options, as shown in the example on the combustion of methane in Table 1.

The three options focus on three different ideas, and in this regard, the learner, in answering such a question, would have to differentiate the role that bond formation and bond breaking have on the energy given off during combustion.

As the laboratory is an essential component of education in the sciences, students are expected to gain from their laboratory experience and learn to ask questions about both techniques and patterns of thinking that lead to specific conceptualisations. However, assessing laboratory knowledge remains a challenge, especially since the assessment should be based on relevant demonstrable laboratory knowledge rather than through theoretical knowledge. One way to enable such assessments is to get students to design experiments that have real-world linkages. An

example of such an assessment[1] (Cuadros & Yaron, 2005), available as a web resource for teachers today, involves getting students to plan experiments that test soil samples for arsenic, a highly toxic pollutant found in well water in Bangladesh. A large portion of the rural population in this Third-World country depends on wells for their drinking and personal needs. Teachers get students to carry out the virtual experiment, using a downloaded app. However, the activity also makes clear that the actual testing for arsenic concentration in drinking water in the real world is better addressed by testing for arsenic concentrations in the soil, which is considerably higher than that present in groundwater.

Getting students to plan the experiment and then carry out their plan provides them with an opportunity to integrate different concepts in chemistry (stoichiometry, limiting reagents) in an attempt to solve a tangible real-world problem at hand. The process of assessment can also be helped along by employing computer-based resources, such as applets, which takes the strain of real-time monitoring and assessment of all students in a chemistry laboratory in one sitting. Yet another way of assessing the planning process can also involve viva voce assessments that are conducted after the students have planned and carried out their plans.

  • [1] Adapted with kind permission from Dr. Cuadros and Dr. Yaron. ChemCollective, GravimetricDetermination of Arsenic Info, 2005, Jordi Cuadros and Dave Yaron.
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