Developing practical skills in the chemistry laboratory

How do we prepare students for practical skills they conduct in the laboratory?

Practical skills involve psychomotor development, as they typically involve handling chemicals, glassware, and instrumentation. But how do we prepare students for this work, and do we give them enough time to develop these skills?

Farmer and Frazer analysed 126 school experiments (from the old O-level Nuffield syllabus) with a view to categorising practical skills and came up with some interesting results.[1] Acknowledging that some psychomotor tasks include a cognitive component (they give the example of manipulating the air-hole collar of a Bunsen burner while judging the nature of the flame for a particular task at hand) they identified 65 psychomotor tasks and 108 cognitive tasks from the experiments studied. Some of these psychomotor tasks are defined as having a key role, in that the success of the experiment is dependent on the successful completion of that task, reducing the number of psychomotor skills to 44. Many of these key tasks were required in only a few experiments, so the set was again reduced to number of frequent key tasks – those occurring in more than 10 experiments. The 14 frequent key tasks subsequently identified are described in their table below.

Data from Education in Chemistry (Ref 1)
Data from Education in Chemistry (Ref 1)

Thus of the 65 psychomotor skills listed, only 14 are defined as frequent key tasks, limiting the opportunities for pupils to develop the skills associated with completing them. Indeed this paper goes on to demonstrate that in an assessment of 100 pupils, there was very poor demonstration of ability in correctly completing the practical tasks, which they attribute to the design of the syllabus and the limited opportunity to do practical work.

This article prompts me to think again: how do we prepare students for the laboratory skills aspect of practical work? I think the most common approach is to demonstrate immediately in advance of the student completing the practical, explaining the technique or the apparatus and its operation. However, demonstration puts students in the mode of observer; they are watching someone else complete an activity, rather than conceptualising their own completion. It also relies on the quality of the demonstrator, and is subject to local hazards, such as time available, ability to see and hear the demonstration, and so on. Therefore, there may be benefit in shifting this demonstration to pre-lab, allowing students time to become accustomed to a technique and its nuances.

Such pre-labs need to be carefully designed, and actively distinguished from any pre-lab information focussing on theory, which has a separate purpose. At Edinburgh, two strategies are planned.

The first is on the development of core introductory laboratory skills: titrations involving pipetting and buretting; preparing standard solutions including using a balance; and setting up Quickfit glassware to complete a distillation. Pre-lab information is provided to students in the form of videos demonstrating each technique, with key steps in each procedure highlighted in the video. Students will be required to demonstrate each of the three procedures to their peers in the laboratory, while their peer uses the checklist to ensure that all aspects of the task were completed appropriately. The purpose here is to incorporate preparation, demonstration, and peer-review into the learning of core lab skills, as well as to set in mind early on in students’ university careers the correct approach and the appropriate glassware to use for basic laboratory techniques. The approach includes students’ videoing their peers as part of the review process using mobile phones; and the video recording will subsequently be used as evidence for issuing students with a digital badge for that technique (more on that at the project homepage).

The second approach is to develop the laboratory manual beyond its traditional textbook format to be an electronic laboratory manual, with pre-lab demonstrations included. More on that project to come soon.

In designing pre-lab activities for skills development, the aim is to move beyond “just demonstrating” and to get students thinking through the approaches they will take. The reason for this is guided by work done by Beasley in the late 1970s. Beasley drew from the literature of physical education to consider the development of psychomotor skills in chemistry. He studied the concept of mental practice as a technique to help students prepare for the laboratory.[2] Mental practice is based on the notion that physical activity requires mental thought, and thus mentally or introspectively rehearsing an activity prompts neural and muscular responses.[3]  Students were assigned to groups where they conducted no preparation, physical preparation, mental preparation, and both physical and mental preparation. They were tested before and after completing a lab on volumetric analysis. Beasley reported that students who students entering college from school were not proficient in completing volumetric analysis based on accuracy of their results. Furthermore, there was no significant difference in post-test scores of treatment students (which were all better than students who did no preparation), suggesting that mental preparation was as effective as physical preparation.

Those interested in reading more on this topic may enjoy two reviews by Stephen DeMeo; one in J. Chem. Ed.[4] and an elegant piece “Gazing at the hand” in Curriculum Inquiry.[5]

References

[1] A. Farmer and M. J. Frazer, Practical Skills in School Chemistry, Education in Chemistry, 1985, 22, 138.

[2] W. Beasley, The Effect of Physical and Mental Practice of Psychomotor Skills on Chemistry Student Laboratory Performance, Journal of Research in Science Teaching, 1979, 16(5), 473.

[3] J. B. Oxendine, Physical education. In Singer, R. B. (Ed.), The psychomotor domain: Movement behavior. Philadelphia: Lea and Feberger, 1972.

[4] S. De Meo, Teaching Chemical Technique: A review of the literature, Journal of Chemical Education, 2001 78(3), 373.

[5] S. De Meo, Gazing at the Hand: A Foucaultian View of the Teaching of Manipulative Skills to Introductory Chemistry Students in the United States and the Potential for Transforming Laboratory Instruction, Curriculum Inquiry, 2005, 35, 3.

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2 thoughts on “Developing practical skills in the chemistry laboratory

  1. Great post! I feel like this is the opposite end of a process that I’m involved with – setting a laboratory practical exam to assess lab skills. I think I have a different perspective because I’m not currently involved with developing lab skills, and I think it’s quite useful when trying to grapple with mark schemes. Always easier not to be influenced by what you ‘think’ they should know/do.
    I am very interested in the use of videos in pre-labs – we do similarly. One of the main issues I find with assessing lab skills is that staff have differing opinions on how to do techniques or set up glassware. A trivial example might be whether to clamp the condenser on a reflux. Do you intend to use the videos as the ‘one true correct way’ to do the lab technique or can you accept variations that may be conveyed by lab demonstrators? A lot of our students find these variations useful (if they save time) or frustrating (because they then try to do the technique ‘right’ depending on who is in the lab. It makes assessing lab work quite tricky as well.

    1. Thanks, am excited to see how it goes.

      The point about the “one right way” has caused us a lot of time and anguish. Our approach for the year 1 lab activity will be that students have to draw from the video a procedure that is pretty prescriptive; so in a sense it is “the right way”. These procedures are drawn from documented sources: school experiment prescriptions, Vogel, Chemistry Olympiad documentation, etc. Intern was meticulous about every step of the process being based on an authoritative source.

      But what we hope to do in the coming weeks of Camtasia editing (joy) is to provide a reason for each of these decisions. That way, the hope is that if students in their later work at project or research level decide they want to do a different way, they will at least know what the purpose of that particular step was, and how it may be accommodated.

      That’s the intention anyway, I’ll reflect on success of that after a few weeks of editing!

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