If you’re measuring the scale and the map distance, you are essentially copying the length of the scale segment onto a line between the two points. Notice both of these have a similarity to the actual compass and straightedge construction. Or, you could eyeball the scale, or use your thumb and finger to approximate its copies. What are the problems that are solved by the use of this skill? Answer Distance QuestionsĪ few years ago I and another teacher adapted a lesson from Dan Meyer that based these problems in the statement: “the compass measures distance.” Bay Area College Map Lesson Plan (PDF) A question asks, “How far is College of Marin from SFSU?” How do you do that? We could use a ruler, measure the map distance, measure the scale, and find the proportion. Let us bring the interesting problems into the now. What a student stuck in these types of classes must think! The future is promised to be full of interesting problems, but the present must be slogged through.
But learning “building blocks” too often slips into disconnected procedure practice. The justification usually becomes “you’ll need it later.” Not only is this thoroughly unsatisfying to the learner, but sometimes when we get to ‘later’ we treat that topic too as disconnected procedure. And indeed, pretty soon the unit will have constructing a parallel line through a given point and constructing a perpendicular through a point. These are treated as building blocks, implicitly promising more detailed constructions later. In Geometry, the unit on constructions usually begins with demonstrations and practice copying a line segment, copying an angle, bisecting a segment, bisecting an angle.
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