Toggle navigation
Log out
Log in
Join
View Cart
Store
Classroom Resources
Notice and Wonder
Illuminations
Problems of the Week
Problems to Ponder
Innovative Lessons and Activities
Classroom Conversations
Tips for Teachers
Math Sightings
Video Lessons
Publications
Featured Books
Advertise
Mathematics Teacher: Learning and Teaching PK-12
Journal for Research in Mathematics Education
Mathematics Teacher Educator
Institutional Subscriptions
Rights and Permissions
Write, Review, Referee
Legacy Journals and Blogs
Standards & Positions
Principles to Actions
Position Statements
Catalyzing Change
Standards for Mathematics Teacher Preparation
Curriculum Focal Points
GAISE II
Focus in High School Mathematics
NCTM Standards
Advocacy
Policies and Recommendations
Advocacy Toolkit
Advocacy and Legislation
ESSER - District Solutions
Every Student Succeeds Act - ESSA Toolkit
NCTM Social Justice and Equity Resources
Capitol Hill Day 2023
Research
Research Briefs & Clips
Linking Research & Practice
Research Conference
Research Monographs
Journal for Research in Mathematics Education
Continuing the Journey
Conferences & Professional Development
NCTM Annual Meeting & Exposition
Professional Development Resources
National Conferences
Research Conference
Virtual Conference
Interactive Institutes
Speaking at NCTM Events
Webinars
Professional Services
NCTM District Solutions
NCTM Teacher Education Program Review Training
NCTE-NCTM Joint Conference on Elementary Literacy & Mathematics
Exhibit, Advertise, Sponsor
Book Study
Grants & Awards
Funding Opportunities
About Mathematics Education Trust
Browse All Grants
Giving Opportunities
Special Events
Lifetime Achievement Award
Social Justice and Mathematics
Membership
Individuals
Schools and Districts
Group Content Access
About
Affiliates
News & Calendar
Career Center
Get Involved
Support Us
MyNCTM
About
Affiliates
News & Calendar
Career Center
Get Involved
Support Us
MyNCTM
Log In
About
Affiliates
News & Calendar
Career Center
Get Involved
Support Us
MyNCTM
Join Now
View Cart
NCTM Store
Toggle navigation
MENU
Classroom Resources
Notice and Wonder
Illuminations
Problems of the Week
Problems to Ponder
Innovative Lessons and Activities
Classroom Conversations
Tips for Teachers
Math Sightings
Video Lessons
Publications
Featured Books
Advertise
Mathematics Teacher: Learning and Teaching PK-12
Journal for Research in Mathematics Education
Mathematics Teacher Educator
Institutional Subscriptions
Rights and Permissions
Write, Review, Referee
Legacy Journals and Blogs
Standards & Positions
Principles to Actions
Position Statements
Catalyzing Change
Standards for Mathematics Teacher Preparation
Curriculum Focal Points
GAISE II
Focus in High School Mathematics
NCTM Standards
Advocacy
Policies and Recommendations
Advocacy Toolkit
Advocacy and Legislation
ESSER - District Solutions
Every Student Succeeds Act - ESSA Toolkit
NCTM Social Justice and Equity Resources
Capitol Hill Day 2023
Research
Research Briefs & Clips
Linking Research & Practice
Research Conference
Research Monographs
Journal for Research in Mathematics Education
Continuing the Journey
Conferences & Professional Development
NCTM Annual Meeting & Exposition
Professional Development Resources
National Conferences
Research Conference
Virtual Conference
Interactive Institutes
Speaking at NCTM Events
Webinars
Professional Services
NCTM District Solutions
NCTM Teacher Education Program Review Training
NCTE-NCTM Joint Conference on Elementary Literacy & Mathematics
Exhibit, Advertise, Sponsor
Book Study
Grants & Awards
Funding Opportunities
About Mathematics Education Trust
Browse All Grants
Giving Opportunities
Special Events
Lifetime Achievement Award
Social Justice and Mathematics
Membership
Individuals
Schools and Districts
Group Content Access
Discovering the Area Formula for Triangles
Log In
Not a member?
Join Now