Comparative thinking is one of our first and most natural forms of thought. When we are infants, one of the first differences we must identify is that between mother and other. Without the ability to make comparisons—to set one object or idea against another and take note of similarities and differences—much of what we call learning would quite literally be impossible.
You may be wondering why we want to look so closely at comparative thinking. What makes it so special? The answer lies in the research of renowned educators Robert Marzano, Debra Pickering, and Jane Pollock (2001). By compiling the available research on effective instruction, Marzano, Pickering, and Pollock found that strategies that engage students in comparative thinking had the greatest effect on student achievement, leading to an average percentile gain of 45 points (p. 7f). More recently, Marzano's research in The Art and Science of Teaching (2007) reconfirmed that asking students to identify similarities and differences through comparative analysis leads to eye-opening gains in student achievement.
Although comparative thinking is a natural operation of our minds and is essential to learning, most students have a difficult time making use of comparisons in school. To better understand how to achieve success when asking your students to make comparisons, it is important to first understand your own attitude toward comparisons and how you use them in your classroom.