Trigonometry develops the concept of trigonometry from simple comparisons to more formal approaches.
Trigonometry: measuring with triangles
Trigonometry: similar triangles
Trigonometry: cosine
Trigonometry: sine
Trigonometry: tan
Trigonometry: using sine
Trigonometry: using cosine
Trigonometry: using tan
Trigonometry: find hypotenuse
Trigonometry: find angles

NLVM: Space manipulatives
Pentominoes
Tessellations
Pattern blocks
Geoboard
Platonic solids
Polyominoes
Golden rectangle

Learn Alberta: Exploring Space series.
Exploring diameter and circumference
Exploring relationships of angles

Learn Alberta: Exploring Measurement series.
Exploring triangles
Exploring trigonometry