EngageNY
Dividing the King’s Foot into 12 Equal Pieces
Apply, apply, apply! A measurement lesson applies a number of concepts to help learn a new construction. Scholars learn to divide a segment into n equal parts using a method that uses the Side Splitter Theorem and a method that...
EngageNY
How Do Dilations Map Segments?
Do you view proofs as an essential geometric skill? The resource builds on an understanding of dilations by proving the Dilation Theorem of Segments. Pupils learn to question and verify rather than make assumptions.
EngageNY
Comparing the Ratio Method with the Parallel Method
Can you prove it? Lead your class through the development of the Side Splitter Theorem through proofs. Individuals connect the ratio and parallel method of dilation through an exploration of two proofs. After completing the proofs,...
Massachusetts Department of Education
Similarity through Transformations
Create the ultimate miniature golf course. The 93-page model curriculum unit from the Massachusetts Department of Elementary and Secondary Education contains nine lessons on understanding similarity in terms of both Euclidean geometry...
Georgia Department of Education
Analytic Geometry Study Guide
Are you looking for a comprehensive review that addresses the Common Core standards for geometry? This is it! Instruction and practice problems built specifically for standards are included. The material includes geometry topics from...
Illustrative Mathematics
Seven Circles III
A basic set-up leads to a surprisingly complex analysis in this variation on the question of surrounding a central circle with a ring of touching circles. Useful for putting trigonometric functions in a physical context, as well as...
Pearson
Performance Based Assessment Practice Test (Geometry)
The incredibly broad topic base of a geometry class makes full-length practice tests like this one, especially ones that include a number of open response questions, invaluable. Here the class can really get that hands-on...
Mathematics Vision Project
Similarity and Right Triangle Trigonometry
Starting with similar triangles and dilation factors, this unit quickly and thoroughly progresses into the world of right triangle features and trigonometric relationships. Presented in easy-to-attack modules with copious application...
Illustrative Mathematics
Dilating a Line
High School geometers verify through experimentation certain properties about dilations. This multi-step problem challenges them to construct examples of dilations to verify specific facts, the final step provides an opportunity to more...
Curated OER
Similarity and Dilations - Discover Properties of Similar Figures
Learners investigate properties of similar figures. In this properties of similar figures lesson, pupils construct similar figures using Cabri Jr. They dilate their figure to create a similar one, and discuss the relationships between...
Curated OER
Dilations with Matrices
Examine dilation with matrices with your class. Learners write a conjecture for how the scale factor determines the size of an image. They then use their conjecture to write a matrix multiplication problem for the illustrated...
Curated OER
Scale Factor Area Perimeter
Mathematicians compare triangles at different scales. In this geometry lesson, learners calculate the area and perimeter of triangles. They use the Ti to make observation of the change that takes place as the triangles are dilated.
Curated OER
Nested Similar Triangles
Nested triangles have been created so that they share a common vertex and vertex angle. Learners drag the endpoints of the side that is opposite the common angle to discover the conditions that make the nested triangles similar. When...
Curated OER
Angles and Similarity
Students identify triangles as similar or congruent. In this geometry lesson, students drag triangles around on the navigator to see the effect of different angles on the shape of the triangle. They discuss angle similarity and angle...
Curated OER
Corresponding Parts of Similar Triangles
Here is a lesson that has learners take a look at corresponding parts of similar triangles, ratios of similarity, reductions and enlargements. They'll manipulate the scale factor (r) to observe the changes in similar triangles and then...
Maths Challenge
Maths challenge.net: Spider Fly Distance
A "three star geometry problem" requiring knowledge of how to complete geometric proofs and some prior math skills to figure the shortest distance between the opposite corners of a cuboid.
Math Open Reference
Math Open Reference: Plane Geometry: Transformations
Explore transformations of a polygon that include: 1) translation 2) rotation 3) reflection and 4) dilation.
Texas Education Agency
Texas Gateway: Coordinate Geometry: Special Segments
The student will derive and use the slope and midpoint formulas to verify geometric relationship that include parallelism and perpendicularity of lines. Then, the student will determine an equation of a line parallel or perpendicular to...
Wolfram Research
Wolfram Math World: Line
This MathWorld site gives Euclid's definition of a line, properties of lines, common terminology, and algebraic representations of lines and their distinctive parts in a cartesian system. The site then goes into detail of different line...
Texas Instruments
Texas Instruments: Investigating Segments in a Right Triangle
In this activity, students review definitions of terms such as right triangle, hypotenuse, midpoint, vertices, and equidistant. They also discover an important characteristic of the midpoint of the hypotenuse.
Texas Instruments
Texas Instruments: Cabri Geometry Tour
In this activity, students use the Cabri software to mark points, draw lines, construct parallel and perpendicular lines, angles, bisectors, and triangles. They learn how to use the tool to measure angles.
Texas Instruments
Texas Instruments: Triangle Midsegment Theorem
Students can use Cabri Jr. to discover that the midsegment of a triangle is parallel to the third side and half the length of the third side.
Texas Instruments
Texas Instruments: Perpendicular Bisector of a Line Segment
Students learn to draw a segment and its perpendicular bisector. They understand right angles and congruent segments. Students observe that changing the length or orientation of the segment changes the perpendicular bisector.
Texas Instruments
Texas Instruments: Dilations in the Plane
A dilation is a transformation that produces a figure with a different size from that of the original figure. In this activity, you will explore the properties of dilations and the relationships between the original and image figures.