It’s important to be able to identify 3D geometric shapes. So, right here, we have what we call a rectangular prism. So, this is a 3D geometric shape, and so, what 3D is, 3D stands for three-dimensional.

And then we other shapes which we call 2D, or two-dimensional. So, like this square right here is two dimensional. It has width, and then it has length.

Next Lesson: Volume and Surface Area of a Cube

The following transcript is provided for your convenience.

So, this right here is the width, and this is the length, and so, it only has two dimensions to it.

Now, three-dimensional objects, like something in real life, like this whiteboard, for example, it has length – I’m going this way, as width going this way, but it’s not perfectly flat, like right here, there’s a thickness to it, and so, there are 3 different dimensions to it. So, this drawing right here is still really only has 2 dimensions to it, but it’s representing something three-dimensional, something you can hold in real life. It has length, width, and height.

And so, this is a rectangular prism, and so, the definition of that is a three-dimensional figure with sides that are all rectangles.

So, this drawing right here is representing something with length, width, and height, and notice that all sides of it are rectangles, so it’s a rectangular prism.

The next lesson: Volume and Surface Area of a Cube, both lessons are included in Practice Tests.