Al’s Awesome Science – Splash Down! – a book for young readers by Jane Clarke.
Another book in the Al’s Awesome Science series.
From the publisher:
Al is experimenting to find out what kind of covering his time machine will need to survive its SPLASH DOWN! back to Earth. Water experiments have a habit of making things very wet and messy. Can they finish their experiments before mum finds out?
Also in the same series:
Al’s Awesome Science: Egg-Speriments!
Al’s Awesome Science: Blast-Off!
Illustrated by James Brown, published by Five Quills, 2018.