3D Figures, Surface Area and Nets
Imagine painting a solid object, like a rock or a cube. You need enough paint to coat the outside surface, right? That's surface area! The surface area of a 3-dimensional (3D) shape is the total number of units, like centimeters (cm2) or inches (in2), needed to cover the outside.
We use "nets" to help us find the area of each side of the object by breaking the 3D shape apart into 2D shapes that when added together, give you the original shape. For example, to find the surface area of a cube, find the area of each square face and then add them together to get a final result. Let's get started!
Math Class Session
These math class lessons will start you out on the right path into our geometry adventure. After watching the math lesson video, continue to practice the concepts using the Geometry Packet, activities, games, projects, word problems... and have fun learning!
Geometry Packet: Section 4
This session uses a packet of lessons that we will be working through in place of a regular workbook. We'll be working on different sections of the packet during each session. In addition to the content in the packet, you'll find homework, activities, quizzes, a study guide and a test to complete at the end when you've finished all the content in the entire packet.
Geometry Activity: Folding a Cube
Take a look at the nets on the template sheet (link below) and see if you can find all the ones that would make a cube! Watch the video, and then when you think you've got them all (HINT: There's 11 that will make a real cube), peek at the answer key under the video.
Geometry Activity: Cut & Paste
Let's practice our new math skills by matching each figure with its net, and then we'll figure out the total surface area. If you'd like, you can make a duplicate of the main sheet and cutout the shapes to make 3D models that match!
Geometry Activity: Guess my Figure?
This is a fun way to really help you visualize shapes in both 2D and 3D using a cut and paste type of activity!
Geometry Game:
All you need is a penny, dime, a sheet of paper and a pencil for this quick, 7-step strategy game that will have you thinking way after you stop playing!
Geometry Puzzle
I remember when I first saw one of these at a science museum. I worked at it for maybe 20 minutes before the light bulb in my head finally went on and I quickly solved the puzzle (to everyone's amazement, including my own!) You can make yours out of a scrap piece of wood (like a paint stir stick or a tongue-depressor size popsicle stick), rope (paracord works well) and two washers or beads. Enjoy!
Geometry Quiz #2
Let's check in and see how much you've learned from the first two sections! First, download the quiz (don't peek at the answer key!) Work through as much of it as you can, and then watch the video below to compare your answers and get a little help if you got stuck.
Geometry Challenge: Egg Timers Problem
I like eggs cooked precisely for 9 minutes. I only have two hourglass timers, one measures 4 minutes, the other 7 minutes. What is the fastest way for me to use the timers to get a perfect 9 minute egg? (Solutions are posted in the following session at the very bottom of the page.)
