Floating and Sinking – Lesson 1and Classwork

Grade: 5
Subject: Science
Date: October 2020
Topic: Floating and Sinking
 

What does floating mean?
Floating means buoyant or suspended in water or air. The word buoyant means able 
or tending to keep afloat or rise to the top of a liquid or gas.  
What does sinking mean?
Sinking means to fall or drop slowly to another level

What causes things to float or sink?
In order to find out why things float you first have to know what a molecule and density is.
 A molecule  the smallest unit of a substance that has all the properties of that substance.
For example, a. water molecule is the smallest unit that is still water.
 A water molecule can be divided into tiny parts called atoms. This produces two hydrogen 
atoms and one oxygen atom.
The term density refers to how tightly or loosely the molecules are packed in an object
Now that we know that lets look into why things float, now everything is made up of molecules;
 all solids, liquids and even air and gaseous states.
Objects with tightly packed molecules are more dense (heavy) than those where the
 molecules are spread out.
 Density plays a part in why some things float and some sink. 
Objects that are more dense than water sink and those less dense float. 
When an object floats, it pushes water out of the way ( displacement ).
Here is a example:
Did you know steel ships float because even though steel is denser than water, their
 hulls are full of air. 
That’s interesting! They sink until enough water has been moved to match the weight of 
steel and air in the hull.
Also Ships float at different heights depending on how heavily laden they are and
 how dense the water is(salt water is more dense than fresh water).
Here is a video to demonstrate today's lesson