Free online education resources
Khan Academy
https://www.khanacademy.org
Especially good for maths and computing for all ages but other subjects at Secondary level. Note this uses the U.S. grade system but it's mostly common material.
BBC Learning
http://www.bbc.co.uk/learning/coursesearch/
This site is old and no longer updated and yet there's so much still available, from language learning to BBC Bitesize for revision. No TV licence required except for content on BBC iPlayer.
Futurelearn
https://www.futurelearn.com
Free to access 100s of courses, only pay to upgrade if you need a certificate in your name (own account from age 14+ but younger learners can use a parent account).
Seneca
https://www.senecalearning.com
For those revising at GCSE or A level. Tons of free revision content. Paid access to higher level material.
Openlearn
https://www.open.edu/openlearn/
Free taster courses aimed at those considering Open University but everyone can access it. Adult level, but some e.g. nature and environment courses could well be of interest to young people.
Blockly
https://blockly.games
Learn computer programming skills - fun and free.
Scratch
https://scratch.mit.edu/explore/projects/games/
Creative computer programming
Ted Ed
https://ed.ted.com
All sorts of engaging educational videos
National Geographic Kids
https://www.natgeokids.com/uk/
Activities and quizzes for younger kids.
Duolingo
https://www.duolingo.com
Learn languages for free. Web or app.
Mystery Science
https://mysteryscience.com
Free science lessons
The Kids Should See This
https://thekidshouldseethis.com
Wide range of cool educational videos
Crash Course
https://thecrashcourse.com
You Tube videos on many subjects
Crest Awards
https://www.crestawards.org
Science awards you can complete from home.
iDEA Awards
https://idea.org.uk
Digital enterprise award scheme you can complete online.
Paw Print Badges
https://www.pawprintbadges.co.uk
Free challenge packs and other downloads. Many activities can be completed indoors. Badges cost but are optional.
Tinkercad
https://www.tinkercad.com
All kinds of making activities.
Nature Detectives
https://naturedetectives.woodlandtrust.org.uk/naturedetectives/
A lot of these can be done in a garden, or if you can get to a remote forest location.
British Council
https://www.britishcouncil.org/school-resources/find
Resources for English language learning
Big History Project
https://www.bighistoryproject.com/home
Aimed at Secondary age. Multi disciplinary activities.
Geography Games
https://world-geography-games.com/world.html
Geography gaming!
The Artful Parent
https://www.facebook.com/artfulparent/
Good, free art activities
Toy Theater
https://toytheater.com/
Educational online games
DK Find Out
https://www.dkfindout.com/uk/?fbclid=IwAR2wJdpSJSeITf4do6aPhff8A3tAktnmpaxqZbkgudD49l71ep8-sjXmrac
Activities and quizzes
Twinkl
https://www.twinkl.co.uk
This is more for printouts, and usually at a fee, but they are offering a month of free access to parents in the event of school closures.