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hello boys and girls welcome to a new natural science lesson natural science unit five lesson

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three changes in matter changes in matter matter can experience physical and chemical changes

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physical changes and chemical changes these changes can be reversible

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or irreversible.

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Reversible or irreversible.

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Cutting is irreversible.

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Stretching is reversible.

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Burning is irreversible.

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And breaking is irreversible.

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Physical changes. Changes of shape. Changes of state. Changes of shape. They can be reversible or irreversible.

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Cutting, bending, stretching, squeezing. Cutting is irreversible. Stretching is reversible. Bending can be reversible or irreversible.

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Squeezing can be reversible or irreversible. It depends.

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The balloon returns to its original shape so it's reversible.

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The pencil does not return to its original shape so it's irreversible.

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In the case of changes of state, they are reversible. Water can change from solid to liquid to gas, from gas to liquid to solid.

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Chemical changes. Two forms of matter react and a new form of matter is created. Chemical changes are irreversible.

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Combustion, oxidation. Combustion, when wood burns, it reacts with oxygen.

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When metal reacts with oxygen, it rusts.

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Thank you very much for listening.

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See you.