K-5 Math Teaching Resources
Triangle Pack
With so many different types of triangles, it can be a challenge for young mathematicians to keep them all straight. Luckily this set of printable triangles is here to engage children in comparing and sorting triangles by their...
National Security Agency
Classifying Triangles
Building on young mathematicians' prior knowledge of three-sided shapes, this lesson series explores the defining characteristics of different types of triangles. Starting with a shared reading of the children's book The Greedy Triangle,...
Shodor Education Foundation
Triangle Area
While the lesson focuses on right triangles, this activity offers a great way to practice the area of all triangles through an interactive webpage. The activity begins with the class taking a square paper and cutting in in half; can they...
Mt. San Antonio Collage
Inequalities in a Triangle
Stuck with triangle proofs? Take a 180° and provide learners with a guided worksheet that tests their knowledge with triangle inequalities. The questions require different types of proofs that range in levels of difficulty.
Illustrative Mathematics
Alike or Different Game
How are a circle and triangle alike? How are they different? These are the types of questions children will answer while playing this fun geometry game. Including a variety of conventional and unconventional shapes, this activity allows...
Curated OER
Exploring Polygons and The Greedy Triangle
Excellent lesson! Anne Linehane's geometry story, The Greedy Triangle, offers an opportunity to practice forming various types of polygons with your learners. Using elastic bands (or Chinese jump ropes), partners form the various shapes...
Mt. San Antonio Collage
Congruent Triangles Applications
Triangles are all about threes, and practicing proving postulates is a great way to get started. The first page of the worksheet provides a brief introduction of the different properties and postulates. The remaining pages contain...
Curated OER
Symmetries of a Quadrilateral I
Learners examine the properties of quadrilaterals from the point of view of rigid motion. Different types of quadrilaterals are characterized by their symmetries, so learners explore the symmetries of a described quadrilateral to...
EngageNY
Putting the Law of Cosines and the Law of Sines to Use
Use the Law of Cosines and the Law of Sines to solve problems using the sums of vectors. Pupils work on several different types of real-world problems that can be modeled using triangles with three known measurements. In the process,...
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...
Shodor Education Foundation
Pythagorean Explorer
Make sure the measurement is right. The interactive provides right triangles with a missing side measurement. Pupils use the given sides and the Pythagorean Theorem to calculate the length of the missing side. After entering the length,...
Curated OER
Symmetries of a Quadrilateral II
Learners investigate the symmetries of a convex quadrilateral in a collaborative activity. Rigid motion and complements are explored as learners analyze different cases of reflections across a line.
Mathematics Vision Project
Module 6: Congruence, Construction, and Proof
Trace the links between a variety of math concepts in this far-reaching unit. Ideas that seem very different on the outset (like the distance formula and rigid transformations) come together in very natural and logical ways. This unit...
Teach Engineering
Straw Bridges
Pairs work as engineering teams to design and build model bridges from drinking straws and tape. In this third segment in a series of 10, teams compete in an attempt to build the strongest bridge. To help with the design, the groups...
Calvin Crest Outdoor School
Survival
Equip young campers with important survival knowledge with a set of engaging lessons. Teammates work together to complete three outdoor activities, which include building a shelter, starting a campfire, and finding directions in the...
Illustrative Mathematics
Sort and Count
Young mathematicians are on their feet and moving around in this primary grade sorting activity. After giving each child an object or picture card, they then sort themselves into groups, counting to see which has the most or least...
Beauty and Joy of Computing
Sprite Drawing and Interaction
Discover how to program objects to move on a screen. In the second lab of a five-part unit, each learner uses block instructions to program a sprite to follow their mouse (cursor). They investigate how to use these same block...