Today's pattern block activity is called "Odd One Out." In this activity, you display four of the pattern blocks. Students study each figure and determine which shape is the "Odd One Out." The caveat-- there isn't necessarily one right answer. In fact, the name of this game is critical thinking. The goal is for students to scrutinize each shape and use discrimination to isolate one shape from the group.

**Here's how it works: **

1. Determine which four shapes to use. **Note:** I find it easiest to choose the four shapes and go through the set to be sure there is a reason for each shape to be the "odd one out".

2. Display the four shapes.

3. Have students determine which shape is the "Odd One Out."

4. After students have had an opportunity to determine an answer, use the "Four Corners" strategy to discuss the students' responses.

a. Assign each shape a corner. **Note:** Create a 8.5" x 11" size paper to make a poster illustrating each shape on cardstock. Laminate them for durability.

b. Ask students to go to the corner which represents their chosen shape.

c. Once assembled, have the students in each corner discuss their reasoning to determine if they all had the same idea or if other ideas exist. Each corner should determine which ideas are true for the set to share with the group.

d. One group at a time, have each corner share their thinking with the class.

**Variation: **Assign each student a letter. Have students determine a reason why their shape is the "Odd One Out." Then have students go to their designated corner and continue with the Four Corners strategy from above.

**Note:** For the "Odd One Out" example above, here is my thinking.

A. The hexagon is the only shape that does not have acute or right angles.

B. The trapezoid is the only shape with unequal sides or unequal angles.

C. The triangle is the only shape without at least one pair of parallel sides.

D. The square is the only shape with right angles.