Last week we began the study of lines with a presentation on points, lines, surfaces and solids. The boys have continued to make progress on their study of lines. First they learned about straight and curved lines. We began with a sensorial experience of straight and curved lines by feeling the edges of square and circle from the geometric cabinet.
Next, they worked together on an exercise in which they sorted the perimeter cards (the thin outline cards) from the geometric cabinet. I bet you thought you'd never use those again after primary! I had to get ours out of the basement. I made labels which state "figures limited by straight lines" and "figures limited by curved lines."
The boys sorted the figures in a kind of mad-dash fashion. I was a little surprised and overwhelmed when it happened. So, next I made them return the cards to me one at a time stating each time "The _______(name of shape) is limited by straight/curved lines" as appropriate.
I held the taut yarn in many positions (over my head, under my rear end, horizontally, vertically, etc.,) and then the boys took a turn doing so.
I tossed the yarn onto the rug and we observed that the shape is now curved. Then the boys took turns tossing the yarn. We made a list of objects in our environment that are limited by straight and curved lines.
I drew them on the board.
The boys drew them on paper, labeled the lines, and then labeled the phrases with their grammar symbol stencils. They store things like this in work binders we keep on a shelf in the school room.
Next we explored this idea with the box of sticks. I let them each find a straight line and a curved line. We changed the position of the lines on the table many times to observe that they remain straight or curved in all positions.
The next day we explored the parts of a straight line. We started by reviewing the difference between straight and curved lines with the blue string. The blue string has found its home in one of our geometry drawers so they can use this to explore at will. Above they are demonstrating a straight line, below a curved line.
Above is a diagram of the rest of the lesson. It is important to note that there is always extra yarn or string hidden in the hands so that you can show which ends can still be extended to infinity.
I drew examples on the board to familiarize them with the written symbols for these parts of a line. And, as with the previous lesson, they drew, labeled and drew grammar symbols for the new nomenclature.
We are continuing our studies this week with the three-positions of straight lines (vertical, horizontal, and oblique).