The Handbook for the New Art and Science of Teaching. Robert J. Marzano

Element 10: Examining Similarities and Differences

      When content is informational, an effective teacher helps students deepen their knowledge by examining similarities and differences. Research has shown that identifying similarities and differences is associated with a gain in student achievement (Alexander, White, Haensly, & Crimmins-Jeanes, 1987; Baker & Lawson, 1995; Gick & Holyoak, 1980, 1983; Halpern, Hansen, & Reifer, 1990; Lee, n.d.; McDaniel & Donnelly, 1996; Raphael & Kirschner, 1985; Ross, 1988; Stone, 1983). Comparing, classifying, finding patterns, and identifying relationships are basic activities that require students to examine similarities and differences (Marzano, 2007).

      There are fourteen strategies within this element.

      1. Sentence-stem comparisons

      2. Summaries

      3. Constructed-response comparisons

      4. Venn diagrams

      5. T-charts

      6. Double-bubble diagrams

      7. Comparison matrices

      8. Classification charts

      9. Dichotomous keys

      10. Sorting, matching, and categorizing

      11. Similes

      12. Metaphors

      13. Sentence-stem analogies

      14. Visual analogies

      The following sections will explore each strategy to provide you with guidelines to effectively implement this element. Read through each before creating a plan for your classroom. Teachers may use the strategies individually or in combination. Remember, these are not merely activities to be checked off; they are methods of creating a practice that combines your art with the science of examining similarities and differences. Reflect on your use of each strategy by filling out the “Strategy Reflection Log” on page 331.

       Sentence-Stem Comparisons

      Students complete sentence stems that ask them to compare and contrast various people, places, events, concepts, or processes. These comparisons can be general or specific, as shown in the following examples.

      • General: House cats are similar to lions because ______. House cats are different from lions because ______.

      • Specific: Sherlock Holmes and Miss Marple are both characters who enjoy solving mysteries, but they are different because ______.

      Consider using the following stem formats in your use of this strategy.

      • ______ and ______ are similar because they both ______.

      • ______ and ______ are different because ______ is ______, but is ______.

      • ______ and ______ are both ______, but different because ______.

      • ______ is similar to ______ because ______. They are different from each other because ______.

      • ______ is similar to ______ but different from ______ because ______.

       Summaries

      A summarizer is a simple graphic organizer that students can use to examine the similarities and differences between two items. It generally has three columns: the left column explicates features that are only found in the first item; the far-right column lists features that are only found in the second item; the middle column should list characteristics that are similar between the two items and include a sentence that summarizes the items’ similarities. Teachers can use this graphic organizer to help students clearly articulate similarities and differences and practice summarizing. Figure 4.6 provides an example.

       Figure 4.6: Example of a completed summarizer.

       Constructed-Response Comparisons

      A constructed-response comparison is a student-generated written response that describes the similarities and differences between two items or ideas. This strategy begins with a simple request by the teacher: “How is ______ similar to and different from ______?” Students must decide which similarities and differences to include in their responses and how to best frame their analysis. More advanced constructed responses can ask students to draw conclusions and indicate why it is important to understand the similarities and differences between the two items.

      Figure 4.7 can help guide students’ use of this strategy.

      Source: Marzano Research, 2016.

Figure 4.7: Comparison words and phrases.

      Visit go.SolutionTree.com/instruction for a free reproducible version of this figure.

       Venn Diagrams

      Students use these visual tools to compare and contrast two or three people, places, events, concepts, or processes. Students can use Venn diagrams for specific, general, abstract, or concrete comparisons. Students write similarities where circles intersect, and they write characteristics unique to the comparison items where the circles do not intersect.

       T-Charts

      Students can use T-charts to compare two objects, ideas, events, or people. Students fill in a T-shaped graphic organizer by writing two topics across the top and details that describe each on either side of a dividing line. Then, once students have gathered several characteristics for each item, they look for similarities and differences between the two items. In several short sentences, students should explain the similarities and differences they see in their T-chart. Additionally, after completing their explanation, students can draw conclusions about the essential similarities and differences between the two things. The conclusion should not list all of the similarities and differences but simply sum up what the student recognizes as the fundamental similarities and differences between the two items. It can be helpful if students write parallel characteristics on each side of the T-chart. For example, when comparing Australia and the United States, students might write the continent each country is found on as the first characteristic. By writing the characteristics in parallel, students will easily be able to identify the similarities and differences between the two items after filling in the T-chart.

       Double-Bubble Diagrams

      Students use this type of diagram to compare the attributes of two people, places, events, concepts, or processes. They write the two things being compared in large circles on the left and right sides of a page. They list common attributes in smaller circles in the center of the page that connect to both large circles. They write unique attributes in smaller circles at the left and right edges of the page that connect only to the larger circle to which they apply.

      See figure 4.8 for a template you can use in your classroom.

      Source: Marzano Research, 2016.

Figure 4.8: Double-bubble diagram template.

      Visit go.SolutionTree.com/instruction for a free reproducible version of this figure.

       Comparison Matrices

      A comparison matrix is an analysis tool that allows students to compare several items by arranging the items’ characteristics side by side. Both elementary and secondary students identify