Compare & Contrast: With regard to what?

*Long post alert*

This strategic look at comparisons is an adaptation of an academic paper I wrote this past year. I dampened it a bit, but I didn’t do a full rewrite. Sorry in advance for the impersonal tone. I had strong enough positive feedback on this one that I thought it might have justified a wider audience. So here it is… we’ll see I suppose. Also, this is a pretty straight-up look at a direct strategic approach to instruction. That is certainly something, as you know, I don’t spend much time on here. The focus here tends to be more on big picture items. However, certain skills are worth careful and detailed guidance. I would argue that this is one of those.

Compare And Contrast

Similarities and Differences

No reference to specific teaching and learning strategies would be complete without a reasonable outline of the act of identifying similarities and differences. Perhaps most notable in this category is the best-selling instructional text; Classroom Instruction that Works by Marzano, Pickering and Pollock in 2001. Marzano later even put the practice of identifying similarities and differences -commonly referred to by practitioners as simply comparing and contrasting- on a still higher pedestal by referring to it as the single most effective strategy to increase student achievement. In What Works in Schools: Translating Research into Action, Marzano lists similarities/differences at the top of a chart which boasts a 45 percentile gain for this strategy alone. This notation served to boost this strategy to the single most effective of the nine referred to in the text. To provide some perspective, the second most effective strategy according to Marzano’s work is summarizing and note-taking, which is associated with an overall 34 percentile gain when utilized effectively (82-83).

Wait a second  -trust me, I get it-  meta analysis certainly can be a skewed way to quantitatively look at instructional strategies. But for this examination, let’s get past that and look at this as a foundational book that has found its way into millions of classrooms across the country. These numbers for comparing make the potential value of this teaching and learning process undeniable even in a broad statistical generalization. However, in my experience as a biology instructor and a generalist instructional coach, one key element is often absent from the delivery of strategic comparison. While students are nearly always guided through the identification of similarities and differences between two concepts, the specifics of the relationship of these differences to one another is too often neglected. In short, this relationship is often referred to as the “criteria” from which to differentiate, or what I will refer to as the “with regard to what?” element.

The strategy of comparison, “takes advantage of the natural human capacity to make comparisons.”

According to Chapter Five in The Strategic Teacher by Silver, Strong and Perini, the strategy of academic comparison “takes advantage of the natural human capacity to make comparisons” (71). I actually like this book. I think it deserves a bit more attention.  The dashboard-like feature at the start of each chapter ties things together in an interesting way.  The text contains several interesting ideas about the ways that these thought processes play out in the mind of the student. Comparison allows us to increase memory by the simple fact that two linked ideas last longer than any two ideas left alone. Comparison allows the use of prior knowledge to help make sense of new ideas. Help in making connections and creation of new and unique ideas certainly can be facilitated by this strategy, and finally it helps to make abstract thought visible and easily-overlooked content unavoidable (74). Solid use of the technique is ultimately made more effective through a process that involves:

  • Describing each item separately
  • Identifying similarities and differences using a comparison organizer
  • Forming and discussing conclusions
  • Synthesizing learning by completing a task (71)

The Silver and Strong text continues by solidifying proper use of the strategy by including a step by step approach which early on includes providing students with criteria for analyzing the two items. This is essentially the basis for drawing a comparison between any two things. Examples listed in the text include:  What do they eat? What do they look like? How do they behave? (75).  In my own instruction, this is the point where I might ask students for example; “How does the wing of a bird and the flipper of a whale differ with regard to structure?” This crucial cognitive element requires students to think about why they are drawing the distinction as well as directing them toward differences described in the curriculum that students may not directly discover on their own. However, much as I have noted in my own practice, Silver and Strong ultimately speak to the importance of moving students toward independence by teaching them how to formulate their own criteria for comparison (75).

Two trains took divergent paths...

Convergent or divergent?

In Classroom Instruction That Works, Marzano differentiates between teacher-directed comparison tasks as opposed to student-directed tasks. Both have their place in the repertoire of the instructor, but both tend to give differing results. It stands to reason that if a teacher wishes to have student thoughts and responses revolve around a tighter, more homogenous standard-  then teacher-directed activities would be selected.  In this case, the students would be given the criteria from which to draw their distinctions.  However, if the teacher wishes to encourage divergent and creative thought, student-directed activities would be prescribed.  In student-directed work, the criteria or characteristics from which to differentiate come directly from the student (16-17).

Though Marzano begins with descriptions of simple comparison tasks like the Venn diagram, he ultimately moves on to the far more complex Comparison Matrix (19).  The Matrices are very structured tables that tend to require a close adherence to the given criteria.  In my experience with similar comparison matrices, student responses and discussions tend to be more tightly wound around a few criteria and rarely stray into more creative or original territory.  To me, there also seems to be something about the structure of the matrix that requires a more careful gradual release of responsibility to the students, even though it is more prescribed. In my opinion, the treatment of comparison strategies by Marzano, Silver, and Strong is reasonably thorough and informative. Not all authors give this process the weight it is due. The way I see it, this is perhaps the most effective instructional strategy simply because of the sophistication of thought processing required. Put more simply-  comparison of rigorous content is just plain harder to do than it might at first seem. Ultimately getting it right in the classroom tends to score big points in academic achievement. I see little disconnect in these two realities.

Not enough respect?

Like many attempts to portray teaching and learning as simplistic tasks one can write the classic “how to” manual for, treatment of comparison strategies often falls shy of the mark.  The very popular text by Stephanie Harvey & Anne Goudvis on comprehension and understanding, Strategies That Work, makes very little mention of comparison strategies.  The one solid mention of a single comparison strategy is found within a “strategy lesson” vignette within a chapter devoted to “Synthesizing Thought.” In it, a seventh-grade science teacher is highlighted for teaching students the differences between coral and kelp, two marine organisms. The vignette briefly explains how the teacher utilizes a “three-column form that is similar to a Venn diagram, since they both report similarities in the middle” (149). No mention of ever going deeper with this strategy is mentioned in the text.  My biggest criticism of simplistic organizers like the Venn diagram is the fact that there is little to no opportunity nor suggestion that students should categorize their differentiation along the lines of criteria or characteristics. This tends to allow more potential disconnects in the process. Subsequent examination of student work of this kind often reveals differences without a counterpart in the opposing concept. This is oftentimes the pitfall of simplistic organizers found throughout the Web for easy download from many websites. Teachers may tend to jump to implementation of such tasks without careful forethought into the type of thinking they ultimately want to elicit from their students.

Another crucial aspect of this strategy that is worth mention is the tendency of teachers to hug too tightly to graphic organizers throughout their plan of action with students. Compare/contrast is one skill that tends to be very tied to a few typical graphic organizer forms. While the help these forms provide with organizing complex thought is valuable in the beginning, students should be released from the printed forms as quickly as is feasible. There is little to gain from releasing students too early in the implementation of a sophisticated strategy.  However, staying too long on the crutch of any graphic organizer tends to leave students ill-equipped when faced with situations where there is no pre-existing organizer. I find that after many scaffolded lessons with organizers of increasing complexity, it is valuable for students to begin practicing this strategy on a blank page.  Only then will they be forced to see this type of organization of thought in their head.  Though I release kids from teacher-printed forms as quickly as possible, I do find that my Zoology students tend to gravitate toward one or two basic versions of comparison diagram.  Perhaps this has more to do with the nature of the information they work with in this course…

Students participate in a laboratory application of a comparison strategy.

A zoological example

In a recent example from my classroom (see image above), students were asked to participate in a hands-on examination and dissection of two preserved animal specimens for anatomical comparison. This strategy is not only useful for the study of comparative anatomy; it is imperative for a deep understanding of the structure and function of animal life. This year, instead of two separate dissection & anatomy lab investigations of Arthropods (invertebrate animals including insects and crustaceans), I decided to do both analyses together.

Students charting Arthropod similarities & differences.

In one regard, I felt like this lesson might lead to students experiencing a more shallow analysis of both organisms in one lab setting.  However, I ended up being very pleasantly surprised. Students spent time analyzing the detailed structures of each organism (grasshopper and crayfish) and recording general and specific observations (image directly above). They then were allowed to graphically chart similarities and differences in the way they saw best fit for the task at hand.  All but one group utilized a format very similar to the one we landed on previously in a large group discussion/debrief as being the best for examination of our content (image directly below).  It is important to note when looking at the student artifacts in this case, that even though this was a fairly teacher-directed strategy, enough freedom was allowed so that student responses went beyond mere structural differences that were directly observed.  Many of the comments were inferential toward the supposed physiology of the animals.  Several of these comments were likely a result of prior knowledge.  However, many took structural differences and used these to also infer behavioral differences that would be observed in live specimens.  This is an important leap from the stated task and one that is carefully facilitated in scaffolded steps.

Student comparison diagram of the anatomy, physiology and inferred behavioral characteristics of both a crayfish and a grasshopper.

Stepping into the hypothetical

Even though students were given little direction by this stage of the course, it is interesting to note that nearly all graphic depictions followed that which was decided to be most beneficial to students by students. This somewhat rigid form was then used to organize thought and in no way seemed to limit responses to the concrete things observable in specimens and on the printed page. An examination of some of the characteristics recorded, including the “with regard to” element of the chart, shows a solid grasp of directly-observable concrete structures. You also can notice a few attempts to take these structures into the abstract of how they might influence the performance or behavior of the specimens.

Regardless of application, it is clear that attempts to have students identify similarities and differences in an academic setting is effective in elevating student understanding.  From the research summarized by Marzano and the careful work done by Silver & Strong, to the few small examples of student work from my classroom, there is more support for this strategy than can be ignored.  From early attempts with Venn diagrams to complex exercises in determining and developing criteria for distinction, academic comparison requires a sophisticated set of thought processes.  Engaging students in such rigorous tasks ultimately sets them up to develop a deep understanding of complex content.


*Harvey, Stephanie and Goudvis, Anne. Strategies That Work. Canada: Pembroke PublishersLimited, 2000.
*Marzano, Robert et al. Classroom Instruction that Works: Research-Based Strategies for                                Increasing Student Achievement. Virginia: Association for Supervision and Curriculum Development, 2001.
*Marzano, Robert. What Works in Schools: Translating Research into Action. Virginia: Association for Supervision and Curriculum Development, 2003.
*Silver, Harry et al. The Strategic Teacher: Selecting the Right Research-Based Strategy for Every Lesson. Virginia:  Association for Supervision and Curriculum Development, 2007.
*Compare And Contrast by an untrained eye on Flickr
*Two trains took divergent paths… by Kevin Dooley on Flickr
*Remaining images…  just me.