Sink Versus Float (Part II)

Using all the knowledge that children experimented and learned, they engaged in a challenge to make a boat that can carry 300 pennies, which was about 4 pounds weight. Some of children wanted to challenge themselves more and wanted to create a boat that can carry a double amount of weight: 600 pennies, which was about 8 pounds.


Grand Prize Winners



Sink Versus Float (Part I)

Children have been exploring many different materials and creating various structures. They showed a great interest in making boats. We decided to take on the challenge of making a boat that actually works, meaning it can float on the water.


We discussed what make things sink vs. float. Many children mentioned that objects that are heavy will sink and objects that are light will float. However, is it that simple? We had 2 sets of 10 items as indicated on the pictures below for children to think and record their hypothesis: which items will sink or float. Then we let the children experiment by having them place all the items on the water.
Through the experiment, children realized that concept of sink vs. float is not that simple.






To better understand our result, we graph the result and identified characteristics of different objects.


Sink and float has a lot to do with the relationship between what object goes into the water and how water reacts to that object. In order to understand the relationship, we explored various concepts mentioned below with the children.


What happens if 2 objects that are in equal size has different weights when they get dropped into water?


We dissected a squash to see why the elongated part sinks more than rounded part?


We also experimented how a dough of clay can sink when it is in a ball shape while it can float when it is flattened out.


Water Displacement

We shared a famous story by Aesop, The Crow And The Pitcher. Children were able to observe the water displacement as marble goes into the bottle. Max says “water is going up because the marble is taking up a space”.




We also put water into the syringe and ask children to block the opening and push down on the plunger. Armand said “I can’t push down the water”.



Surface Tension

What happens to a ball when it gets pushed into the water and let it go?
We also asked children what they feel when they move objects around in the water. When you move water using a wide black plastic piece vs. narrow plastic ruler, does it feel the same?
Ilan said “it’s harder to push down water when I push with a huge pot than tin container.”



What Is Mass? by Don L. Curry
Will It Sink or Float? by Melissa Stewart
Floating or Sinking by Charlotte Gillian
Ships: World Encyclopedia
Things That Float And Things That Don’t by Davis Adler