Module 2 builds on students' previous work with units and with functions from Algebra I, and with trigonometric ratios and circles from high school Geometry. The heart of the module is the study of precise definitions of sine and cosine (as well as tangent and the co-functions) using transformational geometry from high school Geometry. This precision leads to a discussion of a mathematically natural unit of rotational measure, a radian, and students begin to build fluency with the values of the trigonometric functions in terms of radians. Students graph sinusoidal and other trigonometric functions, and use the graphs to help in modeling and discovering properties of trigonometric functions. The study of the properties culminates in the proof of the Pythagorean identity and other trigonometric identities.

Find the rest of the EngageNY Mathematics resources at https://archive.org/details/engageny-mathematics.

The purpose of this task is to strengthen students' understanding of area. It could be assigned in class to individuals or small groups or given as a homework exercise to generate interesting discussions the following day. The relatively high levels of complexity and technical demand enhance its instructional value.

"The Core Knowledge Foundation provides open access to content-rich curriculum materials for preschool through grade 8, including the Core Knowledge Curriculum Series™, with many materials now available and many more in development."

You will need to provide your email address to download these amazing resources. CK has aligned their ELA to the Science of Reading in collaboration with Amplify Reading.
*Full Units
*Books for Students
*Teaching Materials
*Scope & Sequence

This site teaches the Geometry of Circles to High Schoolers through a series of 1084 questions and interactive activities aligned to 9 Common Core mathematics skills.

This geometry lesson shows that that an inscribed angle is half of a central angle that subtends the same arc. [Geometry playlist: Lesson 24 of 31]

In Module 3, students learn about dilation and similarity and apply that knowledge to a proof of the Pythagorean Theorem based on the Angle-Angle criterion for similar triangles.  The module begins with the definition of dilation, properties of dilations, and compositions of dilations.  One overarching goal of this module is to replace the common idea of “same shape, different sizes” with a definition of similarity that can be applied to geometric shapes that are not polygons, such as ellipses and circles.

Find the rest of the EngageNY Mathematics resources at https://archive.org/details/engageny-mathematics.

This task shows how to inscribe a circle in a triangle using angle bisectors. A companion task, ``Inscribing a circle in a triangle II'' stresses the auxiliary remarkable fact that comes out of this task, namely that the three angle bisectors of triangle ABC all meet in the point O.

This task is primarily for instructive purposes but can be used for assessment as well. Parts (a) and (b) are good applications of geometric constructions using a compass and could be used for assessment purposes but the process is a bit long since there are six triangles which need to be constructed.

This problem introduces the circumcenter of a triangle and shows how it can be used to inscribe the triangle in a circle. It also shows that there cannot be more than one circumcenter.

This task focuses on a remarkable fact which comes out of the construction of the inscribed circle in a triangle: the angle bisectors of the three angles of triangle ABC all meet in a point.

This is an instructional task that gives students a chance to reason about lines of symmetry and discover that a circle has an an infinite number of lines of symmetry. Even though the concept of an infinite number of lines is fairly abstract, fourth graders can understand infinity in an informal way.

Math Antics has amazing videos to explain concepts for Math. The videos are very clear and explicit and students love them. All of the video lessons are FREE.

There are also follow up exercises, videos and worksheets that students can use to solidify learning - but you will be required to pay $20 a year to access these. hat being said, it's super useful even without a paid account!

The videos are organized by strand, and all are free.

They cover numeracy, arithmetic, algorithms, fractions, mixed numbers, percentages, ratios, geometry, statistics, measurement, exponents, integers & algebra, algebra 1-3

This amazing site from Alberta has interactive for all the strands.
These could be used by students or in small group instruction or as a whole class.

This award winning math site is searchable by grade level (6-8, 9-10, 11-12), course content and activities. It encourages:
Active Learning
- The unique content format makes learning more interactive than ever before. Students can explore, discover and actively engage in problem solving and creativity.
Personalization
- The content can seamlessly adapt to different students, allowing everyone to achieve mastery. A virtual personal tutor gives real-time hints and encouragement.
Storytelling
- Every course has a captivating narrative and is full of colourful illustrations. Discover all the real-life applications of mathematics, and why it is incredibly beautiful.

Just a few topics include:
- Virtual manipulatives (including Canadian money)
- multiplication flash cards
- Fractals
- timeline of mathematics
- graph theory
- Pascal's triangle
- Factris
- Fibonacci
- circles and pi
- origami
- Platonic Solids
- Symmetry
- Probability
- Cylinders

This goal of this task is to give students familiarity using the formula for the area of a circle while also addressing measurement error.

Build your own system of heavenly bodies and watch the gravitational ballet. With this orbit simulator, you can set initial positions, velocities, and masses of 2, 3, or 4 bodies, and then see them orbit each other.

This task applies geometric concepts, namely properties of tangents to circles and of right triangles, in a modeling situation. The key geometric point in this task is to recognize that the line of sight from the mountain top towards the horizon is tangent to the earth. We can then use a right triangle where one leg is tangent to a circle and the other leg is the radius of the circle to investigate this situation.

The following file contains the assets (or resources) to accompany the Sask DLC Grade 9 Mathematics. Please note that this is not the content of the course, but the assets used to support and deliver it. The files are organized in a zipped folder. You can download it and extract the files. Links are also provided to other materials like videos and other suggested resources. 

This task provides a good opportunity to use isosceles triangles and their properties to show an interesting and important result about triangles inscribed in a circle: the fact that these triangles are always right triangles is often referred to as Thales' theorem. It does not have a lot of formal prerequisites, just the knowledge that the sum of the three angles in a triangle is 180 degrees.

The result here complements the fact, presented in the task ``Right triangles inscribed in circles I,'' that any triangle inscribed in a circle with one side being a diameter of the circle is a right triangle. A second common proof of this result rotates the triangle by 180 degrees about M and then shows that the quadrilateral, obtained by taking the union of these two triangles, is a rectangle.