Plane and solid geometry for middle grades: what each figure is, how its parts are named, and the formulas that go with it. Each page carries its own practice set.
What geometry covers here
Geometry studies shape, size, position and the properties that stay true when a figure is moved or resized.
These pages split it three ways: flat figures and their properties, measurement formulas, and the angles and lines that define both.
Grade fit is roughly 4 through 9. The classification pages align with the Grade 5 standard that students “classify two-dimensional figures in a hierarchy based on properties” (CCSS.Math.Content.5.G.B.4).
Polygons and plane figures
- Polygon basics and polygon properties, including how polygons are named by side count.
- Triangles and right triangles.
- Quadrilaterals.
- Circles.
- Similar figures and congruent figures.
Measurement formulas
- Perimeter formulas.
- Area formulas, covering every common shape with worked examples.
- Surface area formulas.
Solids
- Space figures, the overview of three-dimensional shapes.
- Prisms.
- Cylinders, cones and spheres.
Angles, lines and position
- Classifying angles.
- Angles and intersecting lines.
- Pairs of lines, covering parallel, perpendicular and skew.
- Coordinate geometry.
What is not here
No proofs, no trigonometry, and no constructions with compass and straightedge. This is the descriptive and computational layer that comes before a formal geometry course.
For arithmetic, see math. For applied problems, see word problems.