Topic 2: Sink/Float


Density is a measure of mass per unit of volume.

The average density of an object equals its total mass divided by its total volume.

An object made from a comparatively dense material (such as iron) will have less volume than an object of equal mass made from some less dense substance (such as water).

Items with a higher density of 1 will sink

Items with a density below 1 will float

Same size does not equal same density

What was the point of this activity?

The purpose of this activity was to show how the density of water determines whether something sinks or floats. They can see the different variations of density in everyday items.

Explain how you would introduce this to your class?

I would introduce this to my class by asking what the students already knew about density then, holding up items and having them guess whether or not they would sink or float.

Where do you see a student having difficulty with this?

Difficulty in this activity could stem from students not understanding why certain items that appeared heavier floated while others sank, like the Coke vs, Diet Coke example. This could be a little frustrating for them.


What changes or extensions could you do to this activity?

I could extend this activity by having students bring in household items and testing whether they sank or floated. We could even take this activity outside to gather items.

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