Geometry
Explore measurements, transformations, coordinates and geometric relationships through diagrams and worked examples.
14 lessons
Lessons
Use base and height
Measure perpendicular height to compare triangle areas without relying on shape.
Goes with Area
Count area and perimeter
Count filled unit squares for area and exposed edges for perimeter.
Goes with Area builder
Scale similar triangles
Distinguish the scale factor for side lengths from the scale factor for area.
Goes with Triangles & shapes
Read rise over run
Find a line’s slope from coordinate differences and keep the sign.
Goes with Slopes
Scale length, area and volume
Predict how a solid changes when every length is multiplied by the same factor.
Goes with 3D solids
Connect the circle centers
Turn circle tangency into distances between centers, then use a right triangle to find a radius.
Goes with Circle geometry
Follow circle tangency
Build equations from touching circles, then use the stated region to choose the circle that fits.
Goes with Circle geometry
Choose a triangle ratio
Identify opposite, adjacent and hypotenuse before using sine, cosine or tangent.
Goes with Trigonometry
Reason around the unit circle
Use coordinates, signs and identities to compare trigonometric expressions beyond a right triangle.
Goes with Trigonometry
Track a transformation
Follow a rotation around a stated center and check what stays unchanged.
Goes with Transformations
Use coordinate differences
Separate distance from midpoint by using differences for length and averages for location.
Goes with Coordinate geometry
Sum polygon angles
Connect triangle totals to interior angles and one complete exterior turn.
Goes with Polygons
Measure a circle sector
Use the central angle to take the same fraction of circumference or circle area.
Goes with Circle measures
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