##### Jessika Richter

(Lund - Sweden)The short and sweet: I have been a passionate teacher since 2001. I first worked with the National Park Service in Washington (state), then moved to Australia where I completed my DipEd at the University of Melbourne and then taught at Hailebury ...

## Geometry

** Description:**Lesson Plans and Creative Activities for Geometry Classroom

**Last Updated:**

**Subject(s):**- Mathematics
- Mathematics > Geometry

**Educational Level(s):**- Grades 9-10 / Ages 14-16
- Grades 11-12 / Ages 16-18

- high
- 9th
- 10th
- secondary
- freshman
- sophomore
- teen
- 11th
- 12th
- senior

**Instructional Component Type(s):**- Curriculum: Lesson Plan

- Contributed By: Isaac Newton

### Point P Where You Like

** Description:**An interesting property about area and an arbitrary point on a triangles interior is explored in this activity

**Last Updated:**

**Subject(s):**- Mathematics
- Mathematics > Calculus
- ...

**Educational Level(s):**- Grades 9-10 / Ages 14-16
- Grades 11-12 / Ages 16-18

- high
- 9th
- 10th
- secondary
- freshman
- sophomore
- teen
- 11th
- 12th
- senior

**Instructional Component Type(s):**- Curriculum: Lesson Plan

An interesting property about area and an arbitrary point on a triangles interior is explored in this activity

### Snake Eyes

** Description:**An interesting problem that has students find the area of a particular section of a circle that resembles the pupil of a snake eye. The result is rather surprising, because the area does not involve pi.

**Last Updated:**

**Subject(s):**- Mathematics
- Mathematics > Applied Mathematics
- ...

**Educational Level(s):**- Grades 9-10 / Ages 14-16
- Grades 11-12 / Ages 16-18

**Instructional Component Type(s):**- Curriculum: Lesson Plan

An interesting problem that has students find the area of a particular section of a circle that resembles the pupil of a snake eye. The result is rather surprising, because the area does not involve pi.

### Security Cameras

** Description:**Students use the relationship between central angles and inscribed angles in a circle to solve a problem involving the installation of security cameras in an art gallery.

**Last Updated:**

**Subject(s):**- Mathematics
- Mathematics > Calculus
- ...

**Educational Level(s):**- Grades 9-10 / Ages 14-16
- Grades 11-12 / Ages 16-18

**Instructional Component Type(s):**- Curriculum: Lesson Plan

Students use the relationship between central angles and inscribed angles in a circle to solve a problem involving the installation of security cameras in an art gallery.

### A Cute Triangle

** Description:**A clever puzzle which has students investigate the least number of smaller acute angled triangles you can dissect a triangle into.

**Last Updated:**

**Subject(s):**- Mathematics
- Mathematics > Geometry
- ...

**Educational Level(s):**- Grades 6-8 / Ages 11-13
- Grades 9-10 / Ages 14-16
- ...

**Instructional Component Type(s):**- Activity: Graphic Organizer/Worksheet

A clever puzzle which has students investigate the least number of smaller acute angled triangles you can dissect a triangle into.

### Square Peg, Round Peg

** Description:**This activity has students investigate which fits better, a square peg in a round hole or a round peg in a square hole.

**Last Updated:**

**Subject(s):**- Mathematics
- Mathematics > Calculus
- ...

**Educational Level(s):**- Grades 9-10 / Ages 14-16
- Grades 11-12 / Ages 16-18

**Instructional Component Type(s):**- Curriculum: Lesson Plan

This activity has students investigate which fits better, a square peg in a round hole or a round peg in a square hole.

### The Truncated Square

** Description:**Students use the Pythagorean theorem to solve a tricky puzzle involving a square with four isosceles triangles cut from the corners.

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**Subject(s):**- Mathematics
- Mathematics > Geometry
- ...

**Educational Level(s):**- Grades 6-8 / Ages 11-13
- Grades 9-10 / Ages 14-16
- ...

**Instructional Component Type(s):**- Curriculum: Lesson Plan

Students use the Pythagorean theorem to solve a tricky puzzle involving a square with four isosceles triangles cut from the corners.

### The Right Plot

** Description:**A math problem involving the area of an irregular quadrilateral and the Pythagorean Theorem

**Last Updated:**

**Subject(s):**- Mathematics
- Mathematics > Geometry

**Educational Level(s):**- Grades 6-8 / Ages 11-13
- Grades 9-10 / Ages 14-16
- ...

**Instructional Component Type(s):**- Curriculum: Lesson Plan

A math problem involving the area of an irregular quadrilateral and the Pythagorean Theorem

### Two Triangles

** Description:**Students look at two triangles and must prove whether one line is longer than another. The results are surprising, and there are many different ways to prove the answer to be true.

**Last Updated:**

**Subject(s):**- Mathematics
- Mathematics > Geometry

**Educational Level(s):**- Grades 6-8 / Ages 11-13
- Grades 9-10 / Ages 14-16
- ...

**Instructional Component Type(s):**- Curriculum: Lesson Plan

Students look at two triangles and must prove whether one line is longer than another. The results are surprising, and there are many different ways to prove the answer to be true.

### The Goat Problem

** Description:**This problem has students investigate the area of a pasture in which a goat would be able to graze.

**Last Updated:**

**Subject(s):**- Mathematics
- Mathematics > Algebra
- ...

**Educational Level(s):**- Grades 6-8 / Ages 11-13
- Grades 9-10 / Ages 14-16
- ...

**Instructional Component Type(s):**- Activity: Exercise

This problem has students investigate the area of a pasture in which a goat would be able to graze.

### The Square Problem

** Description:**A great problem that combines practice in graphing linear functions with a challenging problem involving the area of a square.

**Last Updated:**

**Subject(s):**- Mathematics
- Mathematics > Graphing
- ...

**Educational Level(s):**- Grades 6-8 / Ages 11-13
- Grades 9-10 / Ages 14-16
- ...

**Instructional Component Type(s):**- Activity: Exercise

A great problem that combines practice in graphing linear functions with a challenging problem involving the area of a square.

### Pie Free Circles

** Description:**A problem involving the area of a crescent. Many students are surprised to discover that their answers do not involve pi.

**Last Updated:**

**Subject(s):**- Mathematics
- Mathematics > Geometry

**Educational Level(s):**- Grades 6-8 / Ages 11-13
- Grades 9-10 / Ages 14-16
- ...

**Instructional Component Type(s):**- Activity: Exercise

A problem involving the area of a crescent. Many students are surprised to discover that their answers do not involve pi.

### Circum Circle

** Description:**A nice problem that encourages students to think backwards. Instead of inscribing a triangle in a circle, the triangle is given, and the student must discover the diameter of the circle.

**Last Updated:**

**Subject(s):**- Mathematics
- Mathematics > Geometry
- ...

**Educational Level(s):**- Grades 6-8 / Ages 11-13
- Grades 9-10 / Ages 14-16
- ...

**Instructional Component Type(s):**- Activity: Exercise
- Activity: Graphic Organizer/Worksheet

A nice problem that encourages students to think backwards. Instead of inscribing a triangle in a circle, the triangle is given, and the student must discover the diameter of the circle.

### Pick a Shape

** Description:**Students investigate Picks Theorem, involving the area of an irregular polygon on a lattice point grid. This problem has students look for patterns, try to establish a formula, and test the formula with a more difficult case. The area of a lattice point Pterodactyl.

**Last Updated:**

**Subject(s):**- Mathematics
- Mathematics > Applied Mathematics
- ...

**Educational Level(s):**- Grades 6-8 / Ages 11-13
- Grades 9-10 / Ages 14-16
- ...

**Instructional Component Type(s):**- Curriculum: Lesson Plan

Students investigate Picks Theorem, involving the area of an irregular polygon on a lattice point grid. This problem has students look for patterns, try to establish a formula, and test the formula with a more difficult case. The area of a lattice point Pterodactyl.

### Paper Crease

** Description:**A fun geometry problem that takes a little creativity to visualize. Students investigate the length of a crease that is formed when you fold a piece of paper corner to corner.

**Last Updated:**

**Subject(s):**- Mathematics

**Educational Level(s):**- Grades 6-8 / Ages 11-13
- Grades 9-10 / Ages 14-16
- ...

- middle
- 6th
- 7th
- 8th
- tween
- high
- 9th
- 10th
- secondary
- freshman
- sophomore
- teen
- 11th
- 12th
- senior

**Instructional Component Type(s):**- Activity: Exercise

A fun geometry problem that takes a little creativity to visualize. Students investigate the length of a crease that is formed when you fold a piece of paper corner to corner.

### Intro to coordinate geometry

** Description:**Intro lesson and worksheet to coordinate geometry

**Last Updated:**

**Subject(s):**- Mathematics
- Mathematics > Geometry

**Educational Level(s):**- Grades 6-8 / Ages 11-13
- Grades 9-10 / Ages 14-16
- ...

- middle
- 6th
- 7th
- 8th
- tween
- high
- 9th
- 10th
- secondary
- freshman
- sophomore
- teen
- 11th
- 12th
- senior

**Instructional Component Type(s):**- Activity: Graphic Organizer/Worksheet
- Curriculum: Lesson Plan

Intro lesson and worksheet to coordinate geometry

### Proving vertical angles conjecture

** Description:**Students will use both inductive and deductive reasoning to prove the vertical angles conjecture

**Last Updated:**

**Subject(s):**- Mathematics
- Mathematics > Geometry

**Educational Level(s):**- Grades 6-8 / Ages 11-13
- Grades 9-10 / Ages 14-16
- ...

**Instructional Component Type(s):**- Curriculum: Lesson Plan

Students will use both inductive and deductive reasoning to prove the vertical angles conjecture

### Pythagorean theorem and the distance formula

** Description:**Students use the pythagorean theorem in order to derive the distance formula. Includes pythagorean theorem practice problems

**Last Updated:**

**Subject(s):**- Mathematics
- Mathematics > Geometry

**Educational Level(s):**- Grades 6-8 / Ages 11-13
- Grades 9-10 / Ages 14-16
- ...

**Instructional Component Type(s):**- Activity: Exercise

Students use the pythagorean theorem in order to derive the distance formula. Includes pythagorean theorem practice problems

### Finding the area of a trapezoid

** Description:**Students cut a parallellogram and then tape it to form a trapezoid. They then answer a series of questions which enable them to discover the area of a trapezoid.

**Last Updated:**

**Subject(s):**- Mathematics
- Mathematics > Geometry
- ...

**Educational Level(s):**- Grades 6-8 / Ages 11-13
- Grades 9-10 / Ages 14-16
- ...

**Instructional Component Type(s):**- Activity: Graphic Organizer/Worksheet

Students cut a parallellogram and then tape it to form a trapezoid. They then answer a series of questions which enable them to discover the area of a trapezoid.

### Geometry Analysis

** Description:**Template for Analysis of Mathematics Programs/Series
Mathematics Core Curriculum
Mathematics Toolkit
Curriculum Guidance Materials & Resources
Template for Analysis of Mathematics Programs/Series

**Last Updated:**

**Subject(s):**- Mathematics
- Mathematics > Geometry

**Educational Level(s):**- Grades 6-8 / Ages 11-13
- Grades 9-10 / Ages 14-16
- ...

- middle
- 6th
- 7th
- 8th
- tween
- high
- 9th
- 10th
- secondary
- freshman
- sophomore
- teen
- 11th
- 12th
- senior

**Instructional Component Type(s):**- Curriculum: Rubric
- Curriculum: Standards

Template for Analysis of Mathematics Programs/Series Mathematics Core Curriculum Mathematics Toolkit Curriculum Guidance Materials & Resources Template for Analysis of Mathematics Programs/Series

### Interactive Math Websites

** Description:**This resource is a list sorted by subject and individual lessons that include web pages for students to obtain extra practice.

**Last Updated:**

**Subject(s):**- Mathematics

**Educational Level(s):**- Grades 6-8 / Ages 11-13
- Grades 9-10 / Ages 14-16
- ...

**Instructional Component Type(s):**- Asset: Index/List

This resource is a list sorted by subject and individual lessons that include web pages for students to obtain extra practice.