Key to Geometry

Key To Geometry - Constructions

Here is a non-intimidating way to prepare students for formal geometry. Key to Geometry introduces students to a wide range of geometric discoveries as they do step-by-step constructions.

Using only a pencil, compass, and straightedge, students begin by drawing lines, bisecting angles, and reproducing segments. Later they do sophisticated constructions involving over a dozen steps—and are prompted to form their own generalizations. When they finish, students will have been introduced to 134 geometric terms and will be ready to tackle formal proofs.

Use Key to Geometry to stimulate elementary students or to provide an excellent alternative or supplement for high school students.

  • Book 1: Lines and Segments 
  • Book 2: Circles 
  • Book 3: Constructions 
  • Book 4: Perpendiculars 
  • Book 5: Squares and Rectangles 
  • Book 6: Angles
  • Book 7: Perpendiculars and Parallels, Chords and Tangents, Circles 
  • Book 8: Triangles, Parallel Lines, Similar Polygons
  • Answers available separately

View sample pages.

Note: Key to... workbooks are now published by McGraw-Hill Education and available for purchase at If you're a customer in a U.S. territory or outside the United States, find ordering information here.

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Key to... [workbooks] are the best math materials I’ve used for L.D. students. — Paula Vanpool, Special Education, Miami, OK