Our school assigned this regardless of what children were doing over the summer. Sometimes they provided books/ sometimes we had to do something.
I found just using a WH Smith A3 colour paper book (about 20 pages) was perfect.
If you're staying at home there is still tons to do.
DD2 photographed butterflies she spied in the garden.
photographed the Robin's nest & baby robins eggs/ fledgelings.
photographed our visiting fox early one morning.
photographed neighbours cat who came by every evening.
photographed sunsets/ sunrises.
Photographed the moon.
She kept a diary of the plants she planted & how they grew over the summer. She wrote about collecting seeds/ dividing plants with me.
She rated films we went to see and reviewed them.
She wrote about going to the park/ play dates/ water balloon fights/ etc...
She drew pictures and made up stories.
We were asked to show 3 examples of maths during the summer - so she showed how to divide a restaurant bill between 4 people (we went out with friends)/ she calculated how much she saved buying her swimsuit on sale in July/ she calculated how much change from £20 for 5 of us going to a matinee film.
She made top ten lists:
Top ten things to do in school.
top ten things to do out of school.
top ten books.
top ten films.
she photographed her house of cards just before it fell, capturing the collapse.
She photographed balancing towers of her toys.
She included paintings/ drawings & photos of clay creations.
HTH