This activity for "How do Fish breathe" is a good way to keep kids interested in learning more about a class pet or any sea life. Listening to the sounds of how fish breathe could fit under the physics part of the science curriculum.
Magnetic number fishing, they add what they catch! As well as addition, develops hand/eye coordination, fine motor--I love this for magnetic letter fishing too! When they catch a letter, they say its name and sound.