|Natl Lib of Virtual Manipulatives|
The National Library of Virtual Manipulatives - alas, does NOT work on Chromebooks... yet. I am hopeful, as this is an awesome resource.
Improving Math Performance with Inside Math (videos and lessons) - The Noyce Foundation created Inside Mathematics to help educators transform their math practices and to help students better understand the meaning behind the math.
Interactivate- Common Core Aligned Lessons - Interactivate (part of Shodor.org) includes activities (online practice) and lessons (a series of well-defined and understandable chunks that do seem to be a complete lesson). Activities and lessons are based upon Common Core, other state standards and NCTM as well.
Learn Zillion - Common Core Aligned Lessons has a growing compilation of Common Core aligned lesson plans and other resources. It appears the lessons start in volume at 3rd grade and up.
Opus Math Problem Bank - Teachers can search by grade level and subject area, and Opus will produce a series of problem, with the associated Common Core standard.
Eureka Math - Common Core Math Maps - Eureka Math provides a complete map curriculum for grades PK to 12, including lessons, videos and scaffolding. Created for the teachers in New York, these comprehensive math plans are aligned to the Common Core and can supplement whatever math curriculum your school has currently adopted.
Thinking a little ahead, it's tax time! Tax Time Lessons for Junior High - With tax season upon us, many teachers may be looking for financial literacy lessons for students. Scholastic, Inc., in collaboration with Intuit and Mint, has posted a collection of junior high lessons in tax basics and financial literacy. They're cross-curricular, too.
What other sites do you rely on that assist you in developing interesting, relevant math lessons?