Mr. Sia's lesson covers 3D figures, including polyhedrons, prisms, cylinders, cones, and spheres. It explains how to create nets for these figures and explores cross sections, demonstrating how slicing a solid with a plane results in different shapes. The lesson also discusses how rotating 2D shapes like rectangles and triangles can form 3D objects such as cylinders and cones.

What is a polyhedron?

• A three-dimensional figure with polygonal surfaces

• A two-dimensional shape with curved surfaces

• A figure with no edges

• A shape with only circular bases

Which of the following is true about a prism?

• It has two parallel and congruent polygonal bases

• It has only one base

• It is always a cube

• Its sides are all triangles

What is a net in the context of 3D figures?

• A tool for measuring angles

• A type of polygon

• A 2D diagram that can be folded into a 3D figure

• A 3D model of a figure

What shape is formed by a cross section of a cone parallel to its base?

• Triangle

• Hexagon

• Circle

• Square

If a cross section of a hexagonal prism is perpendicular to its base, what shape might it be?

• Circle

• Triangle

• Rectangle

• Hexagon

What shape is a cross section of a rectangular prism if the plane is parallel to one of its faces?

• Triangle

• Rectangle

• Circle

• Pentagon

How does a square relate to a rectangle in terms of cross sections?

• A square is not a rectangle

• A square is a type of rectangle

• A square is larger than a rectangle

• A square has more sides than a rectangle

What 3D shape is formed by rotating a rectangle around one of its sides?

• Sphere

• Cone

• Pyramid

• Cylinder

What 3D shape is formed by rotating a right triangle around one of its legs?

• Sphere

• Cube

• Cone

• Cylinder

Which of the following is NOT a 3D figure discussed in the lesson?

• Sphere

• Pyramid

• Ellipse

• Cylinder