A visible thinking routine (VTR) for comparisons

Two very powerful techniques for provoking learning are getting students to make comparisons and using graphic organisers (see Marzano et al, 2001 pp. 14-20).  The process of making comparisons helps with the acquisition and refinement of concepts because it stimulates students to think and rethink the boundary between this and not-this.  It also requires some fairly deep processing of the sort that seems likely to support long term retention of ideas.  The use of graphic organisers helps to facilitate understanding by making it easier for learners to discern the relationships between ideas.  There is consequently strong justification for using comparison tables a lot, and I do.

A standard comparison table with predefined criteria.

Typically, I use a table organised around criteria given by me.  This works well enough but it’s also somewhat unsatisfying precisely because I give the criteria. Marzano suggests this is preferable where convergent thinking is required because the students are unlikely to come up with suitable criteria on their own.  Point taken, but all the same, what we’re presumably shooting for here is students who are capable of defining their own comparison criteria.

I have been developing a visible thinking routine (see Ritchhart et al, 2011) that shows some promise in this direction.

  1. In groups of three or four, students start by generating as many facts as they can about each of the things they are comparing.  Each fact is written in a separate sticky note.
  2. They are then invited to look for correspondences between the facts about each by lining the sticky note up with each other.  It is best to model this with some sticky notes of your own on the board or under a visualiser, and think aloud whilst doing it e.g. “OK, MRI measures energy from water molecules and PET measures energy from a radiotracer…they sort of go together, so I’m going to line these up together…”
  3. Once students have identified some comparisons they can be encouraged to add more facts to match up with any ‘stray’ sticky notes that don’t currently have a corresponding fact about the comparand.

The students have by this point constructed a skeleton comparison table.  The next step is to encourage and support them in distilling and naming their comparison criteria so they can make their comparisons explicit. Depending on the students they might need more or less scaffolding to do this.

The comparison VTR in progress. Students have started identifying correspondences.

Final steps could be:

  • Recording their table, either drawing it up or photographing it;
  • Working as a whole class to draw up a ‘master’ comparison table based on small-group contributions;
  • Translating their table into well-formed written comparisons (stems can be helpful here).

This process has two significant virtues in that (1) the students do more of the thinking since they go all or at least some of the way to working out their own comparison criteria and (2) it makes their thinking processes visible to you – so you can intervene helpfully – and them, which supports metacognition.

I’ve used this approach several times and am satisfied that it results in comparisons that are as good as those that emerge from a pre-prepared table (although it does take a bit longer).  I am unable to say whether it has any significant impact on my students’ more general capacity to think in comparative ways, although it has intuitive appeal. The important point here is that a visible thinking routine needs to become, well, a routine.  I have not yet used this approach consistently enough across a sufficient range of contexts for my students to incorporate into their everyday thinking repertoire and thereby to permit spontaneous use and generalisation.  My next step, therefore, is to review my schemes of learning for next year and see where the opportunities for this might be.

Marzano, R.J., Pickering, D.J. & Pollock, J.E. (2001).  Classroom instruction that works: Research based strategies for increasing student achievement.  Alexandria, VA: ASCD.

Ritchhart, R., Church, M. & Morrison, K. (2011).  Making thinking visible: How to promote engagement, understanding and independence for all learners.  Hoboken, NJ: Jossey-Bass.

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