Sound Effects/Background Music/Copyright-free Video Clips:
https://mixkit.co/
Word search Generator:
https://www.superteacherworksheets.com/generator-word-search.html
Handwritten Fonts:
https://www.dafont.com/theme.php?cat=603
Illustrations/Photos:
https://www.irasutoya.com/
https://jp.freepik.com/
https://www.pexels.com/ja-jp/
MEXT-related sites:
https://www.eigo-net.jp/
https://www.mext.go.jp/a_menu/kokusai/gaikokugo/index.htm
Others:
https://www.englishclub.com/
(I will update this with the rest of the links tomorrow)
Not to hijack your post, but a couple other illustration websites I personally use are https://illustrain.com/ and https://chojugiga.com/ ! Sometimes all the Irasutoya pictures get boring, so I like to switch it up a bit. :)
Thank you for sharing!