As we all know Math concepts build on each other. When it comes to Measuring Segments and the Segment Addition Postulate there are multiple lessons we must pull together to teach this lesson. The videos below do an excellent job of explaining measuring segments using the following methods.
Ruler Postulate 
Segment Addition Postulate 
Pythagorean Theorem 
Distance Formula 
Use a Manipulative to Teach the Measuring Segments
My advice would be to use blocks or cut outs like these to teach this lesson. I think establishing the connection between these realworld things and the algebra behind the geometry make these postulates much easier to learn. If you just go in with and number line and some numbers on the chalk board it probably won’t stick. I even think the measuring segments worksheets you use need to have more realistic pictures and problems in them.
Give them the squares that they can touch and manipulate. They do not have to be anything fancy. You can actually just give them square pieces of precut paper to play around with. Give them a ruler or yard stick, things they can touch and see themselves actually doing in the real world.
The Pythagorean Theorem and the Segment Addition Postulate
We also included a segment addition postulate worksheet below. These will include the problems involving distance formula, the Pythagorean Theorem, and the ruler postulate.
We also are giving you a Measuring Segments Worksheet, Exit Quiz, Bell Work Assignment, a Power Point Presentation, and some Segment Addition Postulate Guided Notes!
These Postulates Come Up Over and Over Again
Make it a lesson they won’t forget because these things come up over and over again in other lessons like…
 Absolute Value
 Constructions
 Operations with Complex Numbers
 Simplifying Radicals
 Irrational Numbers
 Fractions
 Pythagorean Theorem
 Square Roots
The more students hear how to develop strategies, the better they become at doing so.
Seeing these concepts used helps students make connections about the way all math concepts are related.
Here are your Free Resources for this Lesson!
Segment Addition Postulate Worksheet, Word Docs & PowerPoints
To gain access to our editable content Join the Geometry Teacher Community!
Here you will find hundreds of lessons, a community of teachers for support, and materials that are always up to date with the latest standards.
Segment Additions Postulate  Measuring Segments PDFs
13 Assignment Student Edition Measuring Segments ( FREE )
13 Assignment Teacher Edition  Measuring Segments (Members Only)
13 Bell Work Student Edition  Measuring Segments ( FREE )
13 Bell Work Teacher Edition  Measuring Segments (Members Only)
13 Exit Quiz Student Edition Measuring Segments ( FREE )
13 Exit Quiz Teacher Edition  Measuring Segments (Members Only)
13 Guided Notes SE  Measuring Segments ( FREE )
13 Guided Notes Teacher Edition  Measuring Segments (Members Only)
13 Lesson Plan  Measuring Segments and the Segment Addition Postulate (Members Only)
13 Online Activities  Segment Addition Postulate (Members Only)
13 Slide Show  Measuring Segments ( FREE )
Want access to the rest of the materials on Measuring Segments? To download the rest of the materials for this lesson and get updates via email when new lessons come out simply click the image below to Get All of Our Lessons!

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

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

Teaching Dimensions with Super Mario – Geometry

Lesson for the First Day of Geometry Class