PS/IS 686 | Brooklyn, NY

Fourth Grade Math: Tangled Up in Angles

The past two weeks, fourth graders have been immersed in angles.  Last week, they used plastic shapes called Power Polygons.  We looked at the square, which we knew had 90 degree angles.  I then challenged them to use the square to find the measures of all of the other angles in all of the shapes in the set.  It may not seem difficult, but this was without a protractor!

Many started with the right isosceles triangle.  They realized that if they put 2 of the triangles together, they formed a square.  Therefore, the non-right angles had to be 45 degrees each.  They also found 30 degree angles in some shapes by realizing that three put together formed the right angle.  Sometimes they combined angles, such as the 90 and the 30 to find 120 degree angles.  I was amazed at the reasoning they used?

This week, they have been using protractors instead of reasoning  to measure and draw angles.  We have been using a variety of strategies to decide which scale of the protractor to use.

Some students realized that if we look at the direction the angle is opening from, we can find the zero and count up the scale from there.  Others prefer to think about whether the angle is acute or obtuse and then choose the measurement that makes the most sense. If the ray of your angle is pointing to 60 degrees and 120 degrees, and you know your angle is acute, then 60 degrees  must be the correct measurement.

Drawing angles has been a little more challenging than measuring, but once they got the hang of it, they took off.  In 4th grade, students are only responsible for angles up to 180 degrees. However, we have had some discussion of reflex angles, which are angles between 180 and 360 degrees.  When students were a playing a game called Angle Tangle, a game in which students need to estimate angles drawn by their partners, some partnerships decided to try to draw reflex angles, quite a challenge with a protractor that only goes to 180 degrees!

Tomorrow, we will wrap up our geometry and angle unit with a test which has been posted on School Loop all week.  Next week is the State Math Test (May 1 and 2). Please be sure your child is well rested and has a good breakfast.