EngageNY
Unknown Angle Proofs—Proofs of Known Facts
Lead the class in a Greek history lesson with a geometric twist. Pupils relate a short video about geometric properties to modern-day methods of solving for unknown angles. They discuss parallel line theorems and complete...
Curated OER
Angles
Learners identify obtuse and acute angles in comparsion to a right angle. They identify obtuse, acute, and right angles. Pupils use "Shape Measure" to construct obtuse, acute, and right angles. They review line segements to locate right...
EngageNY
Unknown Angle Proofs—Proofs with Constructions
Provide your emerging mathematicians with the tools to learn as they incorporate auxiliary lines to solve unknown angle proofs in this continuing segment. They decipher information from a diagram to uncover the missing pieces and...
Virginia Department of Education
Angles, Arcs, and Segments in Circles
Investigate relationships between angles, arcs, and segments in circles. Pupils use geometry software to discover the relationships between angles, arcs, and segments associated with circles. Class members use similar triangles to...
EngageNY
Fundamental Theorem of Similarity (FTS)
How do dilated line segments relate? Lead the class in an activity to determine the relationship between line segments and their dilated images. In the fourth section in a unit of 16, pupils discover the dilated line...
Geometry Accelerated
Accelerated Geometry Review Sheet
Your geometry learners use their knowledge of various geometric concepts to write proofs. Starting with givens containing parallel line segments with transversals and triangles and quadrilaterals, and the mid-point and distance formulas;...
EngageNY
Properties of Dilations
Investigate dilations to learn more about them. The second segment in a series of 16 provides a discussion of properties of dilations by going through examples. The problem set provides opportunities for scholars to construct dilations.
EngageNY
Informal Proofs of Properties of Dilations
Challenge the class to prove that the dilation properties always hold. The lesson develops an informal proof of the properties of dilations through a discussion. Two of the proofs are verified with each class member performing the...
Curated OER
Transformations in the Coordinate Plane
Your learners connect the new concepts of transformations in the coordinate plane to their previous knowledge using the solid vocabulary development in this unit. Like a foreign language, mathematics has its own set of vocabulary terms...
EngageNY
Construct a Perpendicular Bisector
How hard can it be to split something in half? Learners investigate how previously learned concepts from angle bisectors can be used to develop ways to construct perpendicular bisectors. The resource also covers constructing a...
EngageNY
Informal Proof of AA Criterion for Similarity
What does it take to show two triangles are similar? The 11th segment in a series of 16 introduces the AA Criterion for Similarity. A discussion provides an informal proof of the theorem. Exercises and problems require scholars to apply...
Illustrative Mathematics
Midpoints of the Sides of a Paralellogram
This task asks learners to prove that the segment joining the midpoints of two sides of a parallelogram is both congruent and parallel to an adjacent side of the parallelogram. The activity would be good to use in a discussion about how...
EngageNY
More About Similar Triangles
Determine whether two triangles are similar. The lesson presents opportunities for pupils to find the criterion needed to show that two triangles are similar. Scholars use the definition of similarity to find any missing side...
EngageNY
Reflections
Facilitate creativity in your math class as individuals learn the definition of a geometric reflection and correctly construct a model, as well as its reflected image. They use a perpendicular bisector and circles to elaborate on...
Curated OER
Reflections
Fifth graders create a reflection of a poygon using a Mira. They discover that a line connecting a vertiex of a polygon and the corresponding vertex of its reflection is perpendicular to the line of reflection. Students create a glide...
EngageNY
Complex Numbers and Transformations
Your learners combine their knowledge of real and imaginary numbers and matrices in an activity containing thirty lessons, two assessments (mid-module and end module), and their corresponding rubrics. Centered on complex numbers and...
Mathematics Vision Project
Module 2: Congruence, Construction and Proof
Construct yourself a winning geometry unit. A set of lessons introduces geometry scholars to constructions and proofs with compasses and straightedges. It also covers triangle congruence through transformations. This is the second of...
Kentucky Adult Education
Probability Lesson Plan
Roll the dice with this multimedia math activity on probability. After first viewing a series of three short videos explaining probability, independent events, and dependent events, young mathematicians complete a set...
Virginia Department of Education
Arc Length and Area of a Sector
What do skateboarding and baked goods have in common with math? You can use them to connect half-pipe ramps and cakes to arcs and sectors. Pupils compare the lengths of three different ramp options of a skate park. They calculate the...
Illustrative Mathematics
Base and Height
It is easy to find the area of a triangle where the base and the height are given. But in this resource, it is up to your geometers to identify the base and height of the triangle. In fact, your pupils will learn that there are three...
Virginia Department of Education
Properties of Quadrilaterals
What type of quadrilateral is that? Discover the difference between the types of quadrilaterals. Small groups investigate types of quadrilaterals using geometry software to find their properties. To keep track of the different...
Curated OER
Tiling the Plane
Fifth graders use pattern blocks and triagular grid paper to reivew shape names, be introduced to the concept of a tiling of the plane, and determine which pattern blocks tile the plane. They are asked if they comprehend what a...
Curated OER
Art or Junk? Discovering the Triangle Inequality
Middle schoolers study the triangle inequality. They will identify, compare, and analyze attributes of two and three-dimensional shapes. Then they develop vocabulary to describe the attributes. They also use manipulatives to analyze the...