This site, from a homeschooling mom in England, has a blog and a Charlotte Mason inspired, multi-age nature curriculum. Includes a guide book with weekly observations, readings and activities; plus a guided journal with copywork. There is some religious content, mostly around Christmas and the solstice and equinox.
Free art lessons for elementary ages.
Online reading, math, and spelling curriculum for elementary ages.
Complete math curriculum for jr. high and high school levels.
This subscription site has loads of resources for learning through children's literature.
A website with lesson plans, worksheets, labs, and activities on biology topics.
The website of this museum in Boston has lots of informative articles, videos, and some free less