Illustrative Mathematics
3-D Shape Sort
From the apple on your desk and the coffee cup in your hand, to the cabinets along the classroom wall, basic three-dimensional shapes are found everywhere in the world around us. Introduce young mathematicians to the these common figures...
Illustrative Mathematics
Hexagonal Pattern of Beehives
Young geometers and biologists investigate the math of nature in an activity that is just the bee's knees. Participants will study the tessellations of hexagons in a beehive, along with the natural rationale behind the specific shape....
Illustrative Mathematics
Right Triangles Inscribed in Circles II
So many times the characteristics of triangles are presented as a vocabulary-type of lesson, but in this activity they are key to unraveling a proof. A unique attack on proving that an inscribed angle that subtends a diameter must be a...
Illustrative Mathematics
What is a Trapezoid? (Part 2)
This collaborative activity investigates the meaning of a trapezoid and a parallelogram. It begins by presenting two different definitions of a trapezoid. Learners are to reason abstractly the difference between the two definitions and...
Illustrative Mathematics
Tangent to a Circle From a Point
Learners see application of construction techniques in a short but sophisticated problem. Combining the properties of inscribed triangles with tangent lines and radii makes a nice bridge between units, a way of using...
Illustrative Mathematics
Are They Similar?
Learners separate things that just appear similar from those that are actually similar. A diagram of triangles is given, and then a variety of geometric characteristics changed and the similarity of the triangles analyzed. Because the...
Illustrative Mathematics
Shortest Line Segment from a Point P to a Line L
One of the hardest skills for many young geometers to grasp is to move beyond just declaring obvious things true, and really returning to fundamental principles for proof. This brief exercise stretches those proving muscles as the...
Illustrative Mathematics
Joining Two Midpoints of Sides of a Triangle
Without ever using the actual term, this exercise has the learner develop the key properties of the midsegment of a triangle. This task leads the class to discover a proof of similar triangles using the properties of parallel...
Illustrative Mathematics
Extensions, Bisections and Dissections in a Rectangle
Gaining practice in translating a verbal description into a diagram and then an equation is the real point of this similar triangles exercise. Once the diagram is drawn, multiple methods are provided to reach the conclusion. An effective...
Illustrative Mathematics
A Midpoint Miracle
Young geometers develop one of the fundamental properties of quadrilaterals (connecting side midpoints gives a parallelogram) in this short but thought-provoking exercise. Using a combination of hands-on techniques and abstract algebraic...
Illustrative Mathematics
Regular Tessellations of the Plane
Bringing together the young artists and the young organizers in your class, this instructional activity takes that popular topic of tessellations and gives it algebraic roots. After covering a few basic properties and definitions,...
Curated OER
Connor and Makayla Discuss Multiplication
The commutative property of multiplication applies not only to whole numbers but to fractions as well. Connor and Makayla explore and discuss the idea that 2/3 x 3 is the same as 3 x 2/3. Your 5th grade class will connect with...
Illustrative Mathematics
Right Triangles Inscribed in Circles I
One of the basic properties of inscribed angles gets a triangle proof treatment in a short but detailed exercise. Leading directions take the learner through identifying characteristics of a circle and how they relate to angles and...
Illustrative Mathematics
Seeing is Believing
How many visual models can be used to show multiplication? Three basic kinds of models can be used to represent and explain the equation 4 x (9 + 2). The commentary section provides description and graphics to explain the set...
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
T Points from Directions
Here is a lesson plan that starts with having geometers translate points using compass directions into an accurate picture of the problem. Then they must use their knowledge of the Pythagorean theorem or similar triangles to solve. This...
Curated OER
Reflections and Equilateral Triangles II
Given the lines of symmetry in an equilateral triangle, your learners find where the pre-image vertices are mapped onto the new image. They explore the properties of equilateral triangles, the impact of reflections, and the...
101 Questions
Snail's Pace
Time doesn't fly when you're watching a snail cross a sidewalk. Combining the concepts of the Pythagorean Theorem and the distance, rate, and time formula, learners determine how long it takes a snail to go from one corner of a sidewalk...
Curated OER
Inscribing a Hexagon in a Circle
This activity is a follow-on activity to inscribing a square in a circle. The overall problem is more complex. It deals with geometric constructions, properties of triangles, and regular hexagons. The final part of the activity...
Illustrative Mathematics
Adding Multiples
Mathematicians practice communicating why the sum of two multiples of a number results in another multiple of that number. Encourage learners to construct a viable argument by applying the distributive property or by drawing a diagram....
Illustrative Mathematics
Solar Eclipse
Learners take on the role of astronomers, calculating conditions necessary for a total solar eclipse. Concepts of similar triangles and properties of circles come together as pupils create ratios and use real measurements in determining...
Curated OER
Reflecting a Rectangle Over a Diagonal
Use the handout as guided or independent practice in drawing a reflection of a rectangle over a line. Three rectangles are provided for practice in addition to a critical thinking question.
101 Questions
2010 Guatemalan Sinkhole
Dig deep into a lesson studying volume. Learners view images of a Guatemalan sinkhole that seems too big to be true! Their task is to determine the amount of material needed to fill the hole using information from news articles and videos.
Curated OER
Reflecting Reflections
A triangle rests in quadrant two, from which your class members must draw reflections, both over x=2 and x=-2. This focused exercise strengthens students' skills when it comes to reflection on the coordinate plane.