Schoolwork made by pupils from 1st and 2nd gradeEcole d’Hermeville (twined with Vergetot)

It floats or it sinks ?

A bucket with water .

Students in each class have brought several items of their choice.

The students have sorted them in two piles, depending on whether they thought the object would float or sink.

What is floating ? What is sinking ?

The hypothesis put forward by the children was: When it is big and heavy it sinks. When it's small

and light it floats.

The boat sank and the little plastic tub floated, even with two balls.

Following this first series of observations, we have set aside items that do not meet the expectations of children and we wrote our results on a large sheet:

We have reached the first conclusion:

There is light and small objects that floats (elastics, paper clips, erasers) and heavy objects that float (large piece of wood, clothespin, rule).

Some can also float and sink.

Pupils from 2nd grade experiment :

To test this hypothesis we put in a bucket a big heavy piece of wood and a small metal nail.

According to a student, "the wood absorbs water and eventually sink after a few hours".

After 3 days the wood was still floating. We came to the conclusion that some materials such as wood floats continuously.

This was confirmed by a carpenter who came to our class and told us that only a few species like ebony can sink.

The 1st grade pupils « try » :

With other plastic items, glass, metal, we realized that the shape was important. When the object is hollow, it floats.

Here is a small glass jar filled with marbles that floats.

A problem of shape

To test this hypothesis we did an experiment: we tried with some plasticine.

It sinks when shaped into a ball but floats when it is flat like a dish.

Conclusion from the children: "It's not that simple."

"This is not because it's big and heavy that it will sink but something small and light may not float.

Some materials such as wood still floats.”

For others, the object's shape is important: "It's like a boat hull”. We made a parallel with the huge boats that are made of metal.