Tag lines and angles in the wild, sort shapes by their properties, and fold figures for symmetry.
REMEMBER: A line goes on forever both ways; a ray starts at
a point and shoots one way; a segment is a piece with two endpoints. Two lines are
parallel if they never meet and perpendicular if they cross at a right angle.
Angles come in flavors: right (exactly 90°), acute (less than 90°),
obtuse (between 90° and 180°). A shape has a line of symmetry if it folds
along that line into two matching halves. A shape can have 0, 1, 2, or more lines of symmetry.
Part 1 · Detective Stations
Station 1 — Line Types & Angle Kinds
Point, line, segment, ray. Then acute, right, obtuse. Click through the gallery.
Station 2 — The Shape Sorter
Pick a shape from the gallery. The sorter files it by parallel sides, perpendicular sides,
and angle types. Right triangles land in their own drawer.
Parallel sides
?
Perpendicular sides
?
Right angles
?
Station 3 — Symmetry Studio (folding table)
Pick a figure and propose a fold. If both halves match on top of each other, it’s a line of symmetry;
if one overhangs, it isn’t.
Station 4 — Count All the Symmetry Lines
The studio finds every line of symmetry a figure has. Some have 0, some have 1, some have many.
Part 2 · Detective Challenges
Predict, then lock in. Identify lines, classify shapes, count symmetry lines.
Part 3 · The Machines
Three step-by-step machines. Each step says what to do and why.
Tell a line from a ray from a segment (and know the angle kind)
Classify a shape by parallel/perpendicular sides and angles
Count all the lines of symmetry
Part 4 · Master Detective Quiz
Ten questions. Each wrong answer tells you which station to revisit.
Question 1 of 10Score: 0
Word Box
Point
A single location, with no size. Drawn as a dot.
Line · Ray · Segment
A LINE goes forever both ways; a RAY has one endpoint and shoots one way; a SEGMENT has two endpoints.
Parallel
Two lines in the same plane that never meet, always the same distance apart. Marked with matching arrowheads.
Perpendicular
Two lines that cross at a right angle (90°). Marked with a little square at the corner.
Acute · Right · Obtuse · Straight angle
Less than 90° · exactly 90° · between 90° and 180° · exactly 180°.
Line of symmetry
A fold line so the two halves match. A figure can have 0, 1, 2, or more lines of symmetry.
Right triangle
A triangle with exactly one right angle (the other two are acute).
Regular polygon
All sides equal and all angles equal. A regular n-gon has n lines of symmetry.