Cut the Knot
Cut the Knot!: Geometric Construction With the Compass Alone
This site explains the possible uses of a compass when drawing. There are numerous exercises for using a compass with links to the solutions - click on the red checkmarks for these. The site discusses mathematicians who contributed to...
Wolfram Research
Wolfram Math World: Math World: Geometric Construction
Offers an explanation of what a geometric construction is and what some of the tools are that are used for it, including the traditional straightedge and compass. The site explains how to construct various polygons inscribed within a...
Oswego City School District
Regents Exam Prep Center: Geometric Constructions
Learn all about the basic geometric constructions in this test prep lesson. You will explore line segments and points, and understand key terms like the terms parallel and perpendicular. Construction activities and interactive online...
National Council of Teachers of Mathematics
The Math Forum: Geoboard Activities
Math Forum provides a set of links to sites that are related to geoboard activities. There are several great links to lessons using geoboards. The links provide insight into how to use them, including how to perform various measurements...
Texas Instruments
Texas Instruments: Traditional Copy an Angle: Compass Construction Using Cabri
Use Cabri Jr to copy an angle. The activity is followed by a student-to-student interview/reflection sheet intended to require students to think, talk, and write about why the construction worked. The reflection sheet could be adapted...
Texas Instruments
Texas Instruments: Parallelograms: Discovering Their Properties
Students use the TI-89 with CABRI Geometry to discover properties of parallelograms. They will construct a figure and use the definition to discover the figure is a parallelogram.
Texas Instruments
Texas Instruments: Investigate Triangles and Congruence
Students can use the TI-84 Plus family with Cabri Jr. to prove triangle congruence with SSA.
Illustrative Mathematics
Illustrative Mathematics: G Co Angle Bisection and Midpoints of Line Segments
This task provides a construction of the angle bisector of an angle by reducing it to the bisection of an angle to finding the midpoint of a line segment. Aligns with G-CO.D.12.
Illustrative Mathematics
Illustrative Mathematics: G Co Construction of Perpendicular Bisector
A and B are two distinct points in the plane and line AB is the segment joining them. The goal of this problem is to construct the perpendicular bisector of segment AB. Aligns with G-CO.D.12.
Illustrative Mathematics
Illustrative Mathematics: G Co Origami Equilateral Triangle
The purpose of this task is to explore reflections in the context of paper folding. Each fold is associated with a line of reflection and understanding each step in the construction requires careful analysis of angles and of the...
Illustrative Mathematics
Illustrative Mathematics: G C Locating Warehouse
You have been asked to place a warehouse so that it is an equal distance from three roads on a map. Students must fold a paper so that this point is where two folds intersect, and they must explain why their construction works and why...
Illustrative Mathematics
Illustrative Mathematics: g.co Bisecting an Angle
In this task, students practice bisecting an angle. Includes a GeoGebra worksheet that teachers can use to demonstrate the task. Aligns with G-CO.D.12.
National Council of Teachers of Mathematics
The Math Forum: Paper Folding Activity
This is a lesson plan of paper folding as a method of proof. A Java applet version of the activity can be accessed, giving the actual lengths and angle sizes.
Math Is Fun
Math Is Fun: Constructing a Triangle With 3 Known Sides
Students learn how to construct a triangle with three known sides using a straightedge and a compass. Includes an animated demonstration.