Geometric Constructions
📋 What it is
Constructions build exact figures using only a compass and straightedge — no measuring.
🗣️ Coach says
Constructions are geometry's puzzles: build a perfect perpendicular, bisect an angle, copy a length — using only a compass and an unmarked ruler. No numbers, just careful arcs. It teaches WHY the rules work, not just that they do.
🧠 Memory hook
Compass = same radius = equal distances. Two arcs crossing gives you an exact point every time.
😂 Giggle
Why do geometry teachers love parks?
Because of all the natural angles and parallel paths!
😲 Whoa!
The ancient Greeks proved some things are impossible with just compass and straightedge — like trisecting any angle — a fact not settled for over 2,000 years.
✅ Quick check: What two tools does a classic geometric construction allow — and what is NOT allowed?
Say your answer out loud first — then reveal.
A compass and a straightedge; measuring with a ruler's marks is not allowed.
Constructions rely on equal radii and straight lines, never measured lengths.
🧪 Try it! (2 minutes)
Use a compass to draw two circles of the same radius that cross; the line through the crossings is a perpendicular bisector.