The commands in the Construct menu can be used to construct the range of special triangles, quadrilaterals, and other polygons that are studied in geometry. For example, the Construct | Perpendicular Line command will be grayed out until the appropriate foundational objects are selected-a perpendicular line must pass through a given point and be perpendicular to some other line, so a point and a line must be selected. The menu itself helps direct attention to the requirements of such constructions. They can constructing midpoints and intersections, and parallel and perpendicular lines. ConstructionĪfter becoming familiar with Sketchpad’s toolbox, students can use the Construct menu to focus on constructing shapes that involve increasingly sophisticated properties and relationships. Sketchpad will provide instant feedback-students can use the “drag test” to check their own work, rather than relying on you to evaluate it. The resulting triangle has now been constructed to be an isosceles triangle, not just drawn to look like one! Encourage students to always drag their constructions to make sure they behave as they should. Simple drawing is useful in focusing attention on properties, while constructing allows the creation of robust and precise shapes, which can then be used in future geometric explorations.ĭraw a circle, then use the segment tool to construct two radii and the segment that joins the radius points. This simple introduction to Sketchpad helps build a rich conception of the triangle-so that students might not expect them all to have horizontal bases! Dragging allows students to see the continuous variations that are possible in geometric shapes, and to build visual and spatial imagery that will help them become better problem solvers.Īs students attempt to configure their triangles into, say, isosceles ones, you can develop the distinction between drawing and constructing. Use the Straightedge tool to draw a triangle, and then drag one of the vertices of that triangle using the Arrow tool to create an infinite variety of triangles. Starting with the toolbox, you’ll find the Point, Straightedge (line), and Compass (circle) tools-the building blocks of Euclidean geometry, and the starting points for rich explorations in school geometry and beyond.

Free online geometer's sketchpad