Right Angles

posted Mar 3, 2015, 4:43 PM by Patrick Johnson   [ updated Mar 3, 2015, 4:45 PM ]
The goal for this math lesson was for students to understand what a right angle is and to be able to identify right angles in shapes. 

Step 1
Students were shown items one at a time in a YES group and items in a NO group (concept attainment). Students were only told that the YES group had something all in common that the NO group did not have. They were also told that the sorting rule for the YES group had nothing to do with size or number of sides of shapes.


Step 2
Students were told to keep their predictions of the sorting rule to themselves. They were also told to be prepared to make new predictions if their sorting rule no longer fit the objects being shown.

Step 3
Students were asked to raise their hand if they had a prediction of what the sorting rule was. They were then asked to whisper their prediction to another student who did not have their hand up. Afterwards, I showed several more YES and NO examples.

Step 4
Finally students were shown a list of TESTERS. They voted using their thumbs (up or down) whether the object belonged in the YES or NO group.

Students then had the opportunity to discuss and share their predictions with the class. Students were quick to realize that the YES group had SQUARE CORNERS (right angles) and the NO group didn't.

Together on the projector, students identified which shapes below contained right angles. If you look closer, students dragged squares into the shapes to confirm that the angle was indeed a right angle.

Step 5
Students were then asked to use their geoboards to make shapes with right angles in them. They were also asked to identify the right angles by placing a square tile in the angle.
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