Paul Harris's website page on Simultaneous Learning

https://www.paulharristeaching.co.uk/simultaneouslearning

Recommended book: Simultaneous Learning 

https://www.amazon.com/Simultaneous-Learning-Definitive-Improve-Teaching/dp/0571538681/ref=sr_1_3?crid=2SBCEG83E09GT&keywords=simultaneous+learning+Paul+Harris&qid=1642453921&sprefix=simultaneous+learning+paul+harris%2Caps%2C28&sr=8-3

Also recommended: The Virtuoso Teacher

https://www.amazon.com/Virtuoso-Teacher-inspirational-instrumental-teachers-ebook/dp/B06WP4TNTN/ref=sr_1_2?crid=168SJUJESHZAM&keywords=simultaneous+learning+Paul+Harris+virtuoso+teacher&qid=1642453681&sprefix=simultaneous+learning+paul+harris+virtuoso+teacher%2Caps%2C36&sr=8-2