Show the students a set of objects that can be sorted according to several criteria. Buttons, pretty pasta, and attribute blocks work especially well. Hold up two or three objects and ask the students to describe each one in as many ways as they can. Record the descriptive words on the board or chart paper.
Now choose two of the descriptive words that are mutually exclusive (for example, red and green), and write each on a separate index card. Next make a Venn Diagram by forming two non-overlapping circles with yarn, and place one index card in each yarn circle. Now hold up an object and ask where it should be placed. Repeat with several more objects. Then remove all the objects and the circles.
Then, choose two of the words that are not mutually exclusive (such as big and red), and write each one on a separate index card. This time, make a Venn Diagram with two overlapping circles with yarn and place one index card in each circle. Hold up an object and ask where it should be placed. Once the students are familiar with the process, give each student an object to place.
Next, remove the objects from the Venn Diagram. Now choose two index cards and place them upside down, one in each yarn circle. Without revealing the sorting rule, place several objects in the circles, then ask the students to try to place objects in the circle. If an object is correctly placed, leave it alone; if it is incorrectly placed, quietly remove it. When several objects have been correctly placed, ask for volunteers to tell how they knew where to place the objects.
When the students have correctly identified the sorting rule, turn over the index cards. Then, remove the items one at a time and create a pattern where all the students can see it. After you have repeated the pattern core (for example, small, big, big) three times, ask for volunteers to place the next object in the pattern. Continue the pattern until all the students are comfortable with the process. Ask a volunteer to read the pattern. Repeat with other patterns, using a different core each time. (A selection of appropriate cores is listed in the Unit Overview at the beginning of this unit.)
Finally, give each student several buttons or attribute blocks or pieces of pretty pasta and ask them to make a pattern. You may wish to use color tiles for younger students. Call on a volunteer to read his or her pattern and ask if anyone else has a pattern that is like that one in some way. Encourage several students to read their patterns, encouraging them to use descriptive words and demonstrating how to use generic pattern descriptions such as AB.
As homework, have students look for patterns in their homes and on their clothing and be ready to describe them tomorrow.