Sink or Float is such a popular piece of work at our little yellow school. While on an Autumn walk around our school grounds, the children collected some items for an Autumn Themed Sink or Float. (Sometimes the children call this work 'Sink or Swim'.)
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| Autumn Themed Sink or Float |
The children took turns dropping items into the tub of water. There was much discussion over whether the gourd and the pumpkin would float. Will they? Scroll down to find out!
Our first student grew the gourd he is dropping into the tub in his own garden!
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A gourd grown by this student! It floats!
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| A Rock |
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| A Pine Branch |
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| A Small Pumpkin - It floats! |
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| A Stick |
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| A Pinecone |
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| Another Pinecone |
The only item that did not float was the rock. It sank quickly.
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| Most of our objects floated. Only the rock sank. |
Once we had dropped all our objects into the tub, some children took turns collecting leaves and dropping them into the tub. The leaves float!
Why do items sink or float? In the most simplest terms, each item is made up of molecules. In some items, such as the rock, the molecules are packed together tightly. In other items, such as the pinecone and stick, molecules are more spread out. How closely molecules are packed together is called density. Density determines why some things float and others sink.
In our experiment, most of our objects were less dense than water. Only the rock was more dense. Although many children predicted the gourd and pumpkin would sink due to their size, they are hollow inside and filled with air. This enabled them to float.
Things That Float and Things That Don't by David A. Adler is a great book to further explore this concept.
