Unit 21 · Arithmetic Mean
Arithmetic Mean
Mathematics · Grade 7
What You Will Be Able To Do
⚖️Work out the mean, and explain what it actually represents
📍Find the median and the mode, and know when each is better
↩️Work backwards from a mean to a total, or to a missing value
🚩Spot when an average is true but gives a completely false picture
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Put all the values into one pile and share the pile out equally, and what each one receives is the arithmetic mean.
Presenter notes: Open with a statement that sounds impossible: in this country the average family has about 2.3 children. Ask who has seen three tenths of a child. The class will laugh, and then the real question arrives: if no family is like the average, what is the average actually describing? Answering that properly is the whole lesson, and it matters far beyond arithmetic.