Around us are many materials like wood, metal, plastic, glass, and rubber.
Each one differs in hardness, transparency, whether it sticks to a magnet, and whether it floats.
That is why windows use clear glass and tires use springy rubber.
Pick a material to compare its properties and drop it in water to see if it floats or sinks.
Explore Various Materials
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Comparing material properties — hardness, transparency, magnetism, buoyancy
🔍 Materials Are All Different
①Wood is light and floats
②Metal is hard and attracts to magnets
③Glass is transparent — light passes through
④Rubber stretches well
⑤Each material has unique properties
Float or Sink?
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Which materials float and which sink in water
💡 Why Float or Sink?
①Materials lighter than water float
②Heavier materials sink
③Wood, plastic, rubber usually float
④Metal and glass usually sink
Summary
Classifying Materials
Material → unique properties (hardness, transparency, magnetism, weight)
Every material has its own properties
Floating Condition
Lighter than water → floats / Heavier → sinks
Determined by comparing material's weight (density) to water
🎯 Key Points
①Materials differ in color, shape, hardness, transparency
②Only metals (iron) attract to magnets
③Some float, some sink
④Knowing properties helps choose uses
⑤Same shape, different material = different properties
Examples and Unit Test
Example 1
Among wood, metal, and plastic, which material sticks to a magnet?
1
Each material differs in whether it sticks to a magnet.
2
Metals like iron stick to a magnet, but wood and plastic do not.
▸ Metal
Metals like iron stick to a magnet; wood and plastic do not.
Example 2
What happens to a piece of wood and a piece of metal when you put them in water?
1
Each material differs in whether it floats on water.
2
Wood is light and floats, while metal is heavy and sinks.
▸ Wood = floats / metal = sinks
Depending on its properties, a material may float or sink in water.
Unit-test style
Which statement about the properties of materials is correct?
①Every material floats on water
②Metal is hard, and some kinds stick to a magnet
③Light cannot pass through glass
④Wood sticks well to a magnet
⑤All materials have the same properties
▸ ② Metal is hard, and some kinds stick to a magnet
1
Metal is hard, and metals like iron have the property of sticking to a magnet.
2
Metal is heavy and sinks in water (①), glass is clear so light passes through (③), wood does not stick to a magnet (④), and each material has its own different properties (⑤).