What learning tools are fun, have bite-sized chunks, and use exercises?

Recently, I've created a daily habit of using these three learning tools:

- Simply Piano (https://www.hellosimply.com/simply-piano)

- Exercism (https://exercism.org/tracks/elixir)

- Math Academy (https://www.mathacademy.com/)

I find it's easy to use each of them every day, because:

1. I don't feel reluctant to get started, because the start of each session is interesting.

2. I can have a useful session in as little as 15 minutes (although longer is better).

3. The exercises make me feel like I'm actually learning.

Other tools don't have the same effect:

- Duolingo fails on #3

- Anki (which I just started using to learn the Gujarati alphabet) fails on #1

I'd love to find other learning tools that give me the same feeling as the three I mentioned. Do you know of any, for any domain?