the ExplOratorium website unless you have hours to spare! There is so much to investigate, so many interesting and quirky pathways to take, so much useful information and media to aid children's learning.
The real life ExplOratorium is based in San Francisco. (Note to self: must visit San Francisco!) It has travelling exhibitions like the Geometry Playground. Luckily for those of us who don't live in the US, it also has a great website with lots to offer parents, teachers and kids.
The Exploratorium isn’t just a museum, it’s an ongoing exploration of science, art, and human perception—a vast collection of online interactives, web features, activities, programs and events that feed your curiosity.
Choose an activity from the home page, or the interactive page. Let's choose Geometry Playground as an example. That brings up an index page for Geometry Playground where further choices include Geometry Garden, Artists in Residence, Activities and Links etc. You can also explore the Geometry Playground exhibition via the themes of seeing, moving and fitting things together (- a photo essay.)
Each time you visit a page, more activities are offered, many of them short videos of shape- related activities in the real world, others text pages with mathematical activities and explanations kids can try. The Activities and Links page for Geometry Playground is HUGE - there are hands-on activities/lessons on tessellations, symmetry, patterns, shapes etc, all divided into Grade Level (K-2, 3-5, 6-8) and with a short description. By the way, if you're interested in Geometry, make sure you also check out @cybraryman's links page.
Geometry Playground is just one section! There are so many more: Science of Gardening (are your kids fascinated by carnivorous plants? Must see video!), Science at Burning Man, The Tinkering Studio - I love their excellent information on marble machines. And there are hundreds of activities, many interactive. Cuteify, for instance, helped me to investigate the factors that make animals, faces, and even objects cute - or not. I could adjust the size of various elements and work out what the cute factor was. And The Crying Game had me rate a video of a baby according to various criteria, then discussed my responses and compared them with others. Kids will also enjoy learning about Optical Illusions.
You can see all 148 websites and 528 activities via the topics page. I think you'll now agree with my warning at the start of this article. Exploratorium is a comprehensive and fascinating site, a real boon to parents (especially home schoolers) and teachers everywhere.