Starfall.com but updated regularly. It’s a website to teach phonics and basic math that was built in the 90’s and it has been the best website for teaching that

Starfall.com but updated regularly. It’s a website to teach phonics and basic math that was built in the 90’s and it has been the best website for teaching that since then. It’s updated twice a year if that. It’s still using Flash, in 2019. The most valuable, useful content is free but there’s a bunch of extra content for supporters. They have App Store apps which might be where they make their money or the prices they charge for a whole school licence may be high. I don’t know. I have only the sketchiest idea of how long it would take to replicate its functionality and to have a bigger library of content but I sincerely doubt it would take one decent programmer who can draw as well as the average 10 year old longer than three months.