Using Visual Gobbets in Teaching

A gobbet is “an extract of text, a passage of literature, an image, a cartoon, a photograph, a map or an artifact provided as a context for analysis, translation or discussion in an assessment” (Chan 2008). “The student’s task is to identify the gobbet, explain its context, say why it is important, what it reminds them of or whatever else you would like them to comment on” (Biggs and Tang 1999). Gobbets are usually used for assessment.

I used "visual" gobbets in my class in Theory of Structures and Earthquake Engineering. Here are some examples.

In my first meeting in Theory of Structures-I, as my review of basic concepts in Statics and Mechanics of Deformable Bodies, I displayed an image of a beam bridge  and posed the problem to the students: “if you are required to design a simple beam bridge to cross a river, what information would you gather to accomplish your task and how would you use the information?

A Gobbet on Simple Beam Analysis & Design

 The responses from this gobbet include span length, beam material, weight of the person(s), number of persons crossing the bridge at one time, shape and size of the beam, soil type at the beam ends and cost. After listing their responses, I asked them on how the items in the list will be used in the analysis and design of the beam bridge. From this exercise, the students were able to reflect and learned about the relationship of the listed items to concepts in Statics and Mechanics of Deformable Bodies.

• A beam bridge can be modelled as a simple beam with length, L and the weights represented as concentrated loads
• Analysis means solving for reactions and maximum internal forces – moment and shear
• The type of material will specify the material strength (allowable stresses) and mechanical properties (modulus of elasticity)
• Designing the beam means determining the shape and size of the beam
• Various types of design can be done for comparison (strength, cost)

Another gobbet in my Earthquake Engineering class was included in an exam to assess the students’ understanding of structural failure due to earthquakes. This is an exercise on post-earthquake evaluation usually conducted by structural engineers (ASEP) after the occurrence of an earthquake. The students are shown photos of a building damaged due to earthquake. A description of the observed damage is also given. The students are required to assess the condition of the building based on the photos and description and recommend the appropriate post-earthquake posting (Safe, Limited Entry or Unsafe).



 "Safe", "Limited Entry" or "Unsafe"?
nisee.berkely.edu



The third example of a gobbet exercise which I called “Scaling an Earthquake” was applied in the Earthquake Engineering course. One of the learning outcomes of the course is familiarization with the PHIVOLCS Earthquake Intensity Scale (PEIS). A series of photos were displayed to the class and the following problem was posted: “You are tasked to determine the intensity of the earthquake using PEIS. Assign the intensity scale for each photo. Explain your answer.” In this exercise, the students have to read and understand carefully the descriptors for each intensity scale in PEIS and relate them to the photos. 

Rate the Intensity Scale of this Earthquake
                     http://woldcnews.com/

References

Biggs, J. and Tang, C. (1999). Teaching for Quality Learning at University, McGraw-Hill Open University Press
Chan C. (2008) “Assessment: Gobbets”, Assessment Resource Centre, University of Hong Kong [http://arc.caut.hku.hk]: Available: Accessed: 8/27/2012