There are times when one is inspired to change how one teaches a lesson that for years has been successful. I have used the knobbed cylinders for years to introduce the concept of a negative shape. (See Sensorial Materials in the MAM Curriculum.) At the end of the lesson I would stuff an 8½x 11” inch piece of paper into the largest cylinder hole of Block B, then carefully take it out. It vaguely looks like the negative shape.
This morning, I realized that the knob on each knobbed cylinder obscures our seeing the top of the wooden cylinder. I now see each knobless cylinder as both a positive shape and as a sensorial representation of its negative shape. In my old lesson I would state that the negative shape is made of space. Because space is invisible, the negative shape of the cylinder seems to join the space of the room. Using the knobless cylinder as a representation of the negative shape inside a cylinder block serves to separate it visually from the space of the room. The negative shape ends at the top of the hole, so the knobless cylinder is an effective tool for teaching negative shapes.
Use the stuffed paper or the knobless cylinder, or both in your presentation – you choose.