Mathematics Class 8
Proportional Reasoning-2
Draw pie charts, work with many-term ratios, and tell direct from inverse.
14 lessons · ~103 min total
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Lessons in this topic
- 0 Start here A roadmap: pie charts, many-term ratios, and pairs that keep a product. · 3 min You are here
- 1 One circle for the whole set One circle stands for a set, and the turn round it is always 360°, however many things are in the set. · 6 min
- 2 A slice is a share of the turn A group's slice is one member's degree multiplied by how many are in the group. · 7 min
- 3 Draw a chart, then check it closes Count, share the turn, angle each group, draw in order, then add every angle to check it reaches 360°. · 9 min
- 4 What a chart says, and what it holds back A chart alone gives shares, never counts — write the total beside it to get counts back. · 9 min
- 5 Two charts that look the same Multiply every count by the same number, and every chart's shares stay exactly where they were. · 8 min
- 6 When one grows and the other shrinks Two amounts are in inverse proportion when their product stays fixed on every row. · 9 min
- 7 Which kind is it, or neither Divide every row for direct, multiply every row for inverse, and if neither works, it is neither. · 9 min
- 8 Workers and days, speed and time Multiply the given pair, divide by the new amount, then multiply back to check the answer. · 8 min
- 9 A ratio with three parts Multiply every term by the same number. One known amount finds that number. · 7 min
- 10 Share a whole in many parts Add the terms, divide the whole, then multiply each term. · 8 min
- 11 Checkpoint: ratios with many terms Check scaling a many-term ratio and sharing a whole. · 5 min
- 12 The big picture Ten ideas, tied back together. · 6 min
- 13 Track quiz Cheat-sheet table plus a reveal quiz — one question per idea. · 9 min
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