Comparing and Contrasting

Bernie Dodge
Ed Tech Department, San Diego State University
http://edweb.sdsu.edu/people/bdodge/scaffolding.html

Very often you'll find yourself in a situation in which you need to sort out the similarities and differences among a group of events, objects or ideas. A technique that can help you do that is called Semantic Feature Analysis. It's not hard to do at all. Here's how it works: Semantic feature analysis uses charts and grids to help students explore how related words differ from one another. By analyzing semantic features of words, students can master important concepts that will help expand their vocabulary and help them understand words essential to learning concepts in content areas.

Procedure

Step 1: Identify the topic category to be analyzed.

Step 2: On an overhead transparency or on the chalkboard, list in a column some words/phrases related to the topic category.

Step 3: List in a row across the top of the chart some features shared by some of the words/phrases.

Step 4: Model with students an analysis of each related word/phrase in terms of each feature. Put plus or minus signs beside each word/phrase beneath each feature according to the appropriate relationship.

Step 5: Brainstorm with students for additional words/phrases that may be added to the row.

Step 6: Brainstorm with students for additional features that may be added to the row.

Step 7: Complete with students this expanded matrix with plus and minus signs.

Step 8: Discover and discuss with students the uniqueness of each word.

Example 1: Science

This example is from a fourth-grade science class.

1. A category is selected (types of rocks).

2. Some words within the category are listed in a column. In this example, the words include granite, obsidian, limestone, coal, shale, slate, and gneiss.

3. Some features shared by some of the words are listed in a row across the top of the chart. In this example, formed by fire, changed by heat or pressure, and formed from other rocks are listed.

4. Plus and minus signs are placed beside each word beneath each feature (see chart).

5. Additional words are added (e.g., basalt, sandstone).

6. Additional features are added (e.g., with large crystals, black, containing fossils ).

7. The matrix is completed with plus and minus signs.

8. The words are discussed so that students see how the words are similar as well as how they differ. (e.g., Granite is a rock that has large crystals and is formed by fire.)

Example1: Semantic Feature Analysis for Types of Rocks

Rock      Formed    Changed   Formed                                            
          by by     by  by    by                                                
          by Fire   Heat      Other                                             
                    and       Rocks                                             
                    Pressure                                                    
                    sure                                                        
granite   +         -         -                                                 
obsidian  +         -         -                                                 
limeston  -         -         +                                                 
e                                                                               
coal      -         -         +                                                 
shale     -         -         +                                                 
slate     -         +         -                                                 
gneiss    -         +         -