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Here’s a procedure for turning ordinary index cards into “Anglefinders”




4, 5, 6  

Title – Making Angle Finders from Index Cards
By – Karen O.
Primary Subject – Math
Grade Level – 4 – 6

Materials needed:

      Index Cards


    Lined paper to make a list

Objective: Students will use an index card to identify: straight, right, acute and obtuse angles.

I use this lesson as an introduction to angles prior to teaching students how to use a protractor for measuring angles.


      1. I give each student an index card. (4″ x 6″ lined is preferable.) This is no longer an index card but a very special tool called an “Anglefinder.” I really ad-lib this part making it sound very important.
      2. On it, students write each angle name, a definition and a small drawing of it.
      3. I explain the the bottom edge of the Anglefinder is a straight angle, the corner is a right angle, anything bigger than the corner is an obtuse (big) angle, and anything smaller than the corner is an acute (a cute little) angle.
      4. I then give students 10 minutes or so to find as many angles as possible in the classroom using their “Anglefinder”. They must have angles for each type. (Ex. the flag pole to the wall may be an acute angle (inside) or obtuse (outside or bottom), the corner of the door is a right angle, the vent part of the heater has straight angles, etc.)
      5. We discuss and share the angles they have found in the classroom. (You will be surprised at what they discover.)
    6. Homework is to find 5 of each type of angle in their home or bedroom, etc.

E-Mail Karen O. !

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