1. The document is a lesson on calculating volume for rectangular prisms and triangular prisms. It provides the formulas for volume (V=l×w×h for rectangles, V=B×h for triangles where B is the area of the base) and examples of using the formulas to solve problems. 2. Students are asked to practice calculating volumes of different shapes using the given formulas and by finding the area of various bases for triangular prisms. 3. The key aspects covered are defining volume, the volume formulas, and examples of applying the formulas to solve volume problems for different shapes.