A NOTE ON STRUCTURES:

Your structures must not be copied and pasted from the literature. All structures must be drawn in Symyx Draw using ACS Settings.

Symyx Draw is available for free download from www.symyx.com/downloads/ where you register for free and download the Symyx No Fee zip file.

Once downloaded, choose ―Open a new document using a template‖ and load the ACS template from the File menu.

At between 2000 and 3000 words, the essay was a ―big‖ assignment at the second year undergraduate level, which required them to hand in a draft. They had just over three weeks to write the first draft, and a further ten days to edit and improve the essay before the final hand in date. The first drafts were marked and returned to the students with suggestions for improvement and encouragement in the areas where they had done well. The students were also encouraged to contact me about the essay if there were any problems.

While serving as an introduction to the service-learning practical, the essay also tackled new learning areas and honed research skills. Students learnt how to summarize and recontextualise information from different sources, how to write in the academic style, how to reference and how to draw chemical structures using a computer software drawing

programme. Writing the draft essay enabled better quality work on the part of the students who could change and edit their essays to better fulfill the criteria on the assignment sheet, as well as improve their general writing skills. The draft essay also ensured that the students made a start on the essay at least 10 days before the final essay was due, and shoddy, last-minute work became less of a problem. Issues of plagiarism could also be sorted out before the formal submission.

As Bressette and Breton (2001) point out, writing is a particularly powerful tool to encourage active learning in chemistry and that through writing assignments students become familiar with the stylistic requirements of scientific writing. They state that drafts that are evaluated by staff members and returned to the students with comments and suggestions for review, lead to better final papers and increased student comprehension. The drafts were formatively assessed, with many comments and suggestions for improvement, but given a mark according to the rubric found in Appendix D. I emailed the class once the draft essays were marked with general concerns and information on how to conclude the essay with a reflection. The reflection offered the students the opportunity to reflect on the whole experience (the final essay submission was after the service-learning practical had taken place) and gave them a chance to see their own growth process over the course of the term. The reflections also formed part of my data. The email can also be found in Appendix D.

The final draft was due on the Monday following the Thursday afternoon practical with the Grade 12 learners.

3.4.2.4 The Azo Dye Practical: “Parallel Combinatorial Synthesis of Azo Dyes” The practical is based on the laboratory experiment of the same name that appeared in the Journal of Chemical Education, devised by Gung and Taylor (2004). The practical lends itself well to a collaborative and cooperative learning experience. To quote from Gung and Taylor:

―The paradigm of combinatorial chemistry is a powerful research technique that also readily accommodates other desirable educational outcomes. A suitably designed laboratory experience in combinatorial chemistry emphasizes the relationship of structure to molecular properties. It reinforces the concept that data acquisition must often precede a theoretical framework. Finally, it allows each student to work independently, yet leads them to share data and interact collaboratively to reach conclusions‖ (Gung &Taylor, 2004, p1630).

Since the aim of service-learning is to work collaboratively and interact with others to reach conclusions, this kind of practical, where there was space for both individual and group work was ideal. This dye practical was done over two weeks. During the first week each pair of students made a different colour dye and planned for the Grade 12 learners who were coming the following week

The practical had been slightly altered and adapted already, by the organic practical coordinator, for the previous year‘s class and so few changes were needed for the practical manual. What did need to be changed, however, was the fact that since the azo dyes made the previous year were not colourfast, a fixative was needed. After some experiments with different fixatives, I decided upon ferrous sulphate as the fixative for this practical. The adapted manual for this practical, along with the lab report sheet can be found in Appendix E.

The second year undergraduate chemistry students generally do their laboratory practicals in pairs, although they usually submit their own work for assessment. Since their work was done jointly, they were given the option to hand in joint practical reports.

In the practical, the principle of combinatorial chemistry is shown by generating a number of brightly coloured dyes using only one common reaction, the diazo coupling, and two common reactants with small variations in their substituents. Each student bench is turned into an individual ―well‖ in terms of combinatorial chemistry. At the conclusion of this experiment, students were asked to discuss the relationship between chemical structure and function when comparing the dye chemical structures and the cotton strips dyed with their azo dyes. The pedagogical value of this experiment lies in that the structure – function relationship is demonstrated in bright colours, and so there is a

tangible way to see the effect that a small chemical structure change can have (Gung & Taylor, 2004). Figure 3.4.2.4.1 shows the generalized diazo coupling reaction, and Figure 3.4.2.4.2 shows the laboratory layout with the twenty different combinatorial wells A1- D5 and the different substituents and the names of the resulting dyes. For a complete table, with all the molecules, including the probable resultant dye molecules, see Appendix E.

Figure 3.4.2.4.1 The generalized reaction scheme of a diazo coupling (Gung & Taylor 2004, p 1630). The practical report or write-up in this case required the student to draw the mechanism of the azo coupling reaction and discuss the relationship between, colour, chemical structure and the ultraviolet spectra of the compounds.

As part of the preparation for the service-learning component the students completed a pre-reflection and planning task while they were busy with the initial dye preparation. This task was based on a simplified version of Kolb‘s Learning Cycle (Kolb 1984) which has been used as a model for reflection by the Campus Outreach Opportunity League (Eyler and Giles 1999).

Figure 3.4.2.4.2 Table showing layout of combinatorial practical and each possible combination

(adapted from Gung and Taylor 2004). The ―What? So what? Now what?‖ model shown in Table 3.2.4.2.1 prompts the students to think about the concrete experience of doing the practical for the first time (What am I doing?). Understanding the reasons why these skills or concepts are important (So what?), a critical thinking step; and then extending this to plan for the future, in this case the second practical with the Grade 12 learners (Now What?), a decision making step. The ―Now what?‖ section was the most important in terms of forcing the students to plan for and think about the service activity and think of ways to incorporate the learners into the experience. This model is recommended by the HEQC Guide for undergraduate

A1 B1 C1 D1

A2 B2 C2 D2

A3 B3 C3 D3

A4 B4 C4 D4

service-learning and particularly for students with very little knowledge and experience of reflection. This was a successful model to use due to its ease of application (Bender et

al. 2006).

This exercise had the added effect of stimulating interesting dialogue with the students about the specifics of azo-dye making. Each section of the practical was divided into a grid format with space for the students to write their plans and comments (See Table 3.4.2.4.1 and Appendix E.3 for the full-size version). Each student was led from a superficial ―doing‖ approach, where a recipe is followed, a learning approach heavily weighted on the Active Experimentation side of Kolb‘s learning continuum, to a more in- depth approach which incorporates Abstract Conceptualization and Reflective Observation within Active Experimentation and contributes to effectiveness of learning (Kolb 1984).

Table 3.4.2.4.1 Grid that each student completed as a pre-reflection and planning task

WHAT?

 Information/concept

 Synthesis Step

SO WHAT?

 Reasons for doing this, challenges, difficulties

 Importance for me and Grade 12 learner