Math Mammoth Early Geometry (2026 ed)

A self-teaching worktext for grade 3 math. It includes both the instruction (written directly to the student) and a variety of exercises and word problems in the same book.

This book focuses on these three topics: classifying shapes, area, and perimeter. In the first few lessons, students learn, in particular, about quadrilaterals as a category. Next, the book focuses on the area of rectangles and shapes composed of rectangular areas. Students learn about different units for area (both metric and customary) and get hands-on experience on finding the area of rectangles by measuring the sides in inches or centimeters. Next the lessons deal with the area of compound (rectilinear) shapes, whose area can be found by decomposing the shape into (non-overlapping) rectangles. Lastly, students learn perimeter as the “go-around measure”: the total distance when you go or travel around the shape. Several lessons focus on both area and perimeter, to make sure students learn to distinguish between these two concepts. We investigate rectangles that have the same area but different perimeters, and also rectangles that have the same perimeter but different areas.