In their book Classroom Instruction That Works, Robert J. Marzano, Debra J. Pickering, and Jane Pollock present four “forms” of identifying similarities and differences: comparing, classifying, creating metaphors, and creating analogies.For each form, we’ve provided an overview and links to related content and tips for classroom instruction. General links provide information about one or more forms of the strategy.
Also known as compare-contrast, this type of activity requires students to identify important characteristics and then use these characteristics as the basis for identifying similarities and differences. Venn diagrams, matrices, and T-charts are all powerful tools to help students compare.
In the primary grades, students can compare two objects, people, or places based on firsthand experience or experimentation. Students can also begin to compare and contrast after listening to a story.
Students in grades 3-5 begin to encounter the compare-contrast text structure in textbooks across all disciplines. While firsthand experience or background knowledge remains important for conceptual understanding, students also need instruction in recognizing signal words (such as like, unlike, and both) and traditional types of comparison text structure. They will need comprehension strategies as well to deal with this complex text structure.
Finally, students should also learn to write simple compare-contrast essays based on knowledge gained firsthand or from reading. Again, students need explicit instruction in writing skills such as organizing information, using signal words appropriately, and including supporting details.
Exploring Compare and Contrast Structure in Expository Texts
This lesson for students in Grades 3-5 focuses on identifying and analyzing the compare and contrast text structures within expository texts.
Learning Tip #26: Comparison Strategies Support Reading, Writing, and Learning
This page provides an introduction to how comparing supports comprehension skills. It also includes seven strategies for using comparison activities in the classroom. Several of these strategies (such as “experiences and discussion” and “children’s literature”) are appropriate for use in the primary grades as well as upper elementary.
Teacher Vision: Comparison
This article provides an overview of comparison.
This page provides background information on three forms of compare-contrast organizers: column, matrix, and Venn diagram. Each format includes an explanation, an example using factual information, and a blank template for printing. More downloadable graphic organizers for compare-contrast are available from Education Oasis.
Classifying is organizing items or elements into groups based on their similarities. Defining rules for group membership is an aspect of classifying. Graphic organizers that help students classify include tables and “bubble” charts.
Students in the primary grades most often classify items as a result of direct experience, but could also classify characters or objects after listening to a read-aloud or watching a video.
Students in the elementary grades can begin to classify items after reading.
Teacher Vision: Classification
This article describes classification, focusing specifically on classification within science.
Developing Young Children’s Classification and Logical Thinking Skills
This article discusses the way young children classify objects and provides tips for creating classification activities.
Creating metaphors involves understanding and defining how two items are related in a literal or abstract way. While graphic organizers are not as common in this form, they can be helpful for students moving from two seemingly unrelated elements to an abstract relationship.
Metaphors are a complex concept and are often not introduced until the upper elementary grades. The ReadWriteThink lesson highlighted invites younger students to “play” with language, focusing less on the actual definitions of similes and metaphors.
As Slippery as an Eel: An Ocean Unit Exploring Simile and Metaphor
This ReadWriteThink lesson uses fiction and nonfiction books to help primary students (K-2) begin to create metaphors and similes through modeling, guided practice and independent practice in words and drawing. The lesson plan could be adapted for use with other thematic units or with older students.
When creating analogies, students think about the relationship between two items and extend that relationship to another set of items. According to the authors, this is the most complex format for the strategy as it involves thinking about “relationships between relationships.” Again, graphic organizers are useful in guiding students’ thinking.
Like metaphors, analogies are a complex concept and may be too difficult for primary students. However, students can begin to explore this concept by identifying pairs of objects that are alike in similar ways.
Best Teaching Practices: Using Analogies
This article provides a general overview of using analogies to deepen comprehension.
How Is a Hot Dog Like a Shoe?
This lesson plan describes how to introduce the concept of analogies and assist students in creating them. While this site refers to a unit about migration, the general lesson could be adapted for use in many other contexts.
Not specific to any one form of identifying similarities and differences, these links provide general information or information about more than one form of the strategy.
Instructional Strategies That Work: Identifying Similarities and Differences
This site provides an overview of all four forms of the strategy and includes links to graphic organizers for each form.
Similarities and Differences: What This Means for Instruction
This article includes guidelines for how and when to use the four forms of the identifying similarities and differences strategy.
National Council of Teachers of English and International Reading Association: Standards for the English Language Arts
This site lists the 12 English Language Arts Standards for K-12 students. The four forms of identifying similarities and differences meet the following standards: 3, 4, 5, 6, 11, and 12.
Copyright March 2008 – The Ohio State University. This material is based upon work supported by the National Science Foundation under Grant No. 0733024. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. This work is licensed under an Attribution-ShareAlike 3.0 Unported Creative Commons license.