I loved themed learning at any age! From reading Teddy Bear's Picnic and eating outdoors with babies, right through to teens writing essays inspired by concepts in a sci-fi movie they watched or novel they read...
Last week I read The Rainbow Fish to Zeah and the little ones I babysit, then we did some simple related activities.
The Rainbow Fish, with his shimmering scales, is the most beautiful fish in the ocean but he is proud and vain and none of the other fish want to be his friend—until he learns to give away some of his most prized possessions.
Sometimes the activity is so simple it's completed by the end of the story, and other times, we can spend a week or more immersed in the theme of a much-loved book.
When I looked online for activities related to The Rainbow Fish, there were hundreds of free ideas including arts & crafts, colouring pages, worksheets, games, loose parts play, snack ideas, and more! Learning like this is a little like a themed party, but a whole lot less effort!
If you search online for a book title, and "activities" and your approximate age group, you'll see what others have done. Some sites like Twinkl also have themed packs to download. Using a library book and some simple materials you can create a themed learning unit at home for FREE! Have fun!