Plasticine learns how to swim

Sorry your answer is wrong.

Do the experiment and compare the result with your assumption again.

The illustration above shows what happens if you put the figure in the water.

The mass of the figure did not increase nor decrease compared to the ball before. Even if the plasticine has another shape now, it does not displace more water than before. How do we have to change the shape of the ball to displace a higher volume of water?