This is one of my favorite lessons to teach because it is all around us and they know exactly what they are and don't know it. Teaching Dimensions is fun using video games!
How to Teach Dimensions
Let's start with a One Dimensional Lines. Simple, it's the distance between two points. Every time we measure the distance between to things we are using one dimension.
Here's where it gets fun, Two Dimensional Objects!
Ask them how many of them used to have a regular Nintendo System or have seen one before. How many of them have played the original Mario Brothers game? In the game you can tell how tall Mario is and how thick (or fat depending on how well you know your kids  they will laugh) Mario is. However, you can't see how Wide Mario is. He runs and jumps but he never turns to the side so we can see his width. That's because the original Nintendo System and most old game systems were made in Two Dimensions.
Move a few years in the future. The Nintendo 64 comes out or really any Nintendo after that. On these systems we can now see Mario move in all directions. We can see he is wide, he is short, and he has a big belly. That's because Mario is now in 3D or Three Dimensions. He had a height, a width, and a thickness (or length).
You don't have to use this example there are many things you could relate this to. I can guarantee you though if you start talking about video games in class or cell phones or something they use regularly they will be locked in and paying attention! If you want our lesson plans, worksheets, and assessments that go along with this lesson and all of our others simply click the link below to join!
Here is a link to access to Geometry Lesson Plans that work and are Common Core aligned!

Find and Use Slopes of Lines

Teaching Congruent Figures

Triangle Congruence by ASA and AAS

Teaching Perpendicular and Angle Bisectors

Teaching Bisectors in Triangles

Best Geometry Books for Kids

Proving Theorems in Geometry

How to Prove Lines Are Parallel

Teaching Logic in Geometry

Teaching Angle Pairs

Teaching Midpoint and Distance in the Coordinate Plane

Proofs with Uno Cards

Valentine’s Day Math Activity – Classifying Quadrilaterals

Christmas Math Worksheets

Thanksgiving Worksheet for Geometry – Happy Turkey Day!

Halloween Geometry Activities High School

How to Teach Classifying Polygons

Points Lines and Planes

Tessellation Project

The Unit Circle – Hand Trick

Introduction to Trigonometry

Pi Day Top 5 for Geometry Teachers

Polygons in the Coordinate Plane – How to use Geogebra

Teaching Tessellations to Your Geometry Class

3 Ways to Make Your Life Easier as a Geometry Teacher Without More Geometry Worksheets

Reasoning and Proof

Geometry Games – Dance Dance Transversal

Midsegments of Triangles

Planning a Proof

Triangle Congruence by SSS and SAS

Pythagorean Theorem – NFL and Geometry

Inequalities in One Triangle

Parallel Lines Cut by a Transversal – Colorful Flip Book Notes

Measuring Angles PuttPutt Course Design Project

How to Teach Tangent Lines – Graphic Organizer

Segment Addition Postulate

Two Tips to Teach Volumes of Prisms and Cylinders

Parallel Lines and Transversals

Nets and Drawings for Visualizing Geometry – Geometry Nets Project

Ratios and Proportions – Bad Teacher!

Hybrid Flipped Classroom Model

How to Teach Perimeter and Area of Similar Figures – in Jay Leno’s Garage

How to Create a Jeopardy Game

5 Tips for New Teachers

8 Teacher Discounts you don’t want to miss this Summer

Your Students are Cheating with this Math App

How to Setup and Use Google Classroom and Google Forms to Teach Geometry

Special Right Triangles – The Foundation of Everything Trig

How to use Google Forms and Word Clouds to Help your Students Master their Geometry Vocabulary

Interactive Geometry Teaching Techniques

The Magic Octagon – Understand Congruence in Terms of Rigid Motions

Attention Getters to Keep Your Geometry Class Locked in!

Teaching Strategies for your Inclusion Geometry Class without an Intervention Specialist

How to Teach the Properties of Quadrilaterals

How to make Geometry Interesting

How to Teach Circles Using the Common Core Standards?

Full Year of Geometry Lesson Plans

How a Rock Star Geometry Teacher Uses the iPad to Educate

Are you a Geometry Teacher with No Textbooks or Geometry Worksheets?

How to Deal with a Class Clown – Classroom Management Strategies

Geometry Lessons  The Game Has Changed  Common Core Standards

Lesson for the First Day of Geometry Class