Here are some of the sources we enjoy. They are loosely organised into ‘subject’ areas of:

Art / Astronomy / Biology / Chemistry / Electronics / Geography / Geology / History / Math / Physics / Misc.

 ART

Time – Andy Goldsworthy
Wood – Andy Goldsworthy
Rivers and Tides – Andy Goldsworthy
  Sasarau Sasarau – iPhonegrapher
 
Google Art Project Google Art Project
  Art Skills – Fiona Watt
Drawing with Children – Mona Brookes

ASTRONOMY

  Celestial Treasury. From the Music of the Spheres to the Conquest of Space – Marc Lachièze-Rey, Jean-Pierre Luminet and Joe Laredo
  Solar System. A Visual Exploration of All the Planets, Moons and Other Heavenly Bodies that Orbit Our Sun – Marcus Chown
Wonders of the Solar System – Brian Cox
Wonders of the Universe – Brian Cox
Star Atlas – Wil Tirion
Full Moon – Andrew Chaikin
  Astronomy Cast Astronomy Cast – “where we not only tell you what we know, but how we know what we know” – hosted by Fraser Cain & Dr Pamela Gay
When we left earth. The NASA missions – NASA
   NASA NASA – all things space

BIOLOGY

Life in the Undergrowth – David Attenborough
Life in Cold Blood – David Attenborough
  Life of Mammals – David Attenborough
Life of Birds – David Attenborough
  The private life of plants – David Attenborough
  The Blue Planet – David Attenborough
The Amateur Naturalist – Gerald and Lee Durrell
The Amateur Naturalist – Nic Baker
  Life – David Attenborough (BBC)
  Human Body – Robert Winston

CHEMISTRY

The Elements. A visual exploration of every known atom in the universe – Theodore Gray
 
Periodic table of videos Periodic table of videos – Brady Haran & University of Nottingham
Illustrated guide to home chemistry experiments. All lab, no lecture – Robert Thomson

ELECTRONICS

Make: Electronics. Learn by discovery – Charles Platt

GEOGRAPHY

  Full Circle – Michael Palin (This is a collection, but they are also available individually.)

GEOLOGY

Earth. The power of the planet – Iain Stewart
  How the earth made us – Iain Stewart
 
GNS Science Geological and Nuclear Science in New Zealand (YouTube channel)

 HISTORY

Civilisation – Kenneth Clarke

 MATH

  The Story of Math – Marcus du Sautoy
 
Vi Hart  Vi Hart “Mathemusician”
  Mathematics. A human endeavour – Harold Jacobs

 PHYSICS

 
 Minute Physics  Minute Physics “Simply put – cool physics and other sweet science” – Henry Reich
125 projects for the evil genius – Jerry Silver

 MISC.

 
 Khan Academy Khan Academy – “learn almost anything for free”
The Story of Philosophy – Bryan Magee
  Underground – David Macaulay
  The New Way Things Work – David Macaulay
 
The kid should see this The Kid Should See This – “we don’t underestimate kids around here”
 
Brain Pickings Brain Pickings – “cultural curator and curious mind at large”