Which of the following shapes is considered a three-dimensional shape?

A cylinder is a three-dimensional shape because it has length, width, and height, allowing it to occupy space. It is characterized by two circular bases connected by a curved surface. This means that it cannot be represented on a flat plane without distortion; it must be viewed from various angles to appreciate its full form.

In contrast, a circle and a triangle are both two-dimensional shapes. They have only length and width—without height—so they lie flat on a plane. Similarly, a square, being another two-dimensional figure, has equal sides but does not extend into the third dimension either. Understanding the distinctions between two-dimensional and three-dimensional shapes is crucial, especially when discussing geometry in the context of early childhood education. This foundational knowledge lays the groundwork for students to recognize and describe shapes in their environment.