Math Websites:
http://www.youcubed.org - Mathematics & Growth Mindset from Stanford University - research, videos, math tasks, courses for students/parents/teachers
https://achievethecore.org/ - standards-based resources, information, tasks, and professional development
http://www.classroomchef.com - information from the book The Classroom Chef, with plenty of teacher resources
https://tapintoteenminds.com/ - lots of resources including lesson plans, complete with 3-act task videos
https://gfletchy.com/ - content progression videos, tasks, and support!
http://www.desmos.com - site with graphing calculator applications, but also many interactive classroom activities that allow the teacher to see the work of each student
http://www.illustrativemathematics.org - supported by the authors of the CCSS, this site offers rich math tasks, lesson ideas, PD for teachers, and now a free curriculum for grades 6-8 (HS coming out summer 2019!)
https://www.artofmathematics.org/ - resources for inquiry-based and visual math, from an organization supported by the National Science Foundation.
http://www.visualpatterns.org/ - amazing site full of patterns to study and discuss math connections; examples for K-high school
http://makingmathvisible.com/Workshops.html - activities for building 2D and 3D math models
http://www.estimation180.com/ - activities to practice estimating - great discussion and interactive plans for movement and includes videos
https://greatminds.org/ - Home of Great Minds & Eureka math, this is where you should download you modules if you are using Eureka. There are also other resources for teachers and parents!
https://nrich.maths.org/ - site for math tasks for all grade levels
https://www.tabletalkmath.com/ - math conversation starters for home and school
https://clotheslinemath.com/ - number line math activities (on a clothesline!)
https://momath.org/ - The website for the National Museum of Mathematics! (It's in NYC, and still on my bucket list if you're taking a field trip!)
http://www.nysedregents.org/ - resources from past NY Regents Exams (including the past exams)
http://www.problem-attic.com/ - resource to find and use questions from multiple state, national, and international math tests, you can also build assessments using these questions.
General Education/Teaching Websites:
http://www.nysed.gov/ - The NYS Education Department Website
https://www.teachingchannel.org/ - video examples and lessons aligned to standards
https://www.edreports.org/ - a non-profit organization who reviews curricula for alignment, rigor, and usability
https://achievethecore.org/ - supports multiple contents; highlights best practice in instruction;