Unit 16 · Fractions
Fractions
Mathematics · Grade 7
What You Will Be Able To Do
➕Add and subtract fractions, and say why a common bottom is needed
✖️Multiply them, and see why the word OF means multiply
➗Divide them, and explain why the answer often gets bigger
🔀Handle mixed numbers safely by converting them first
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You can only add pieces that are the same size. But multiplying is taking a part of a part, and that works whatever the sizes are.
Presenter notes: Open with the question the class has probably been carrying for a year without asking: why does adding fractions need a common bottom when multiplying does not? Write both rules on the board and ask whether they seem consistent. They do not, which is honest, and by the end of the lesson the class will see that both come out of a single difference. Promise that, because it converts a set of rules into one idea.