Circles

As we continue to explore circles, we also do a classroom project where we collect circular items and use them to find the diameter, radius, and circumference.  One thing that I note though, is that it is helpful to measure them ahead of time, since they are often not an exact measurement.  Depending on how much measuring, estimating, and multiplication with decimals you want to do, dictates the objects you may want to select ahead of time.

The students trace each object onto a piece of paper and label it (blue lid, wipes dispenser, etc).  It helps to have a running chart posted in the room that can be filled in to check answers against.  They then use a ruler to measure the diameter of the circle, divide by 2 to find the radius, and multiply by Pi to find the circumference.  This project can be extended as kids can use different units to measure with.

Teaching Circles with a Read Aloud

To teach circumference, radius, and diameter of a circle, I have a few lessons that I do.  One is to read aloud Sir Cumference and the Knights of the Round Table.  We chart the story as we go along.  (Helpful to have this done ahead of time). This is a fun book that gets the kids thinking about circles and tricks to remember the names of the parts of the circle (Lady Di of Ameter stretches her body across the circle, and the diameter is the measure of her toes to finger tips). 
Then we label a number of circles with diameter and radius.  The next day we discuss our charts and revisit the story.

Movement in Geometry

Teaching flips/reflections, slides/translations, and turns/rotations in the Geometry unit.

The students choose a letter, draw it once and cut it out four times (or trace a stencil), then give an example of this letter from a starting point, making each of these movements.