Proportionally, one doesn't see much of cross multiplying in geometry. The portion of extensive playlist on geometry reviews proportions. Using properties of equality, the video shows why cross multiplying works for proportions.

Concepts

proportional reasoning, proportions, equivalent ratios, ratios

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Additional Tags

math

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Instructional Ideas

• Spend some time going over the different ways to write proportions

Classroom Considerations

• Individuals should be comfortable with ratios and equivalent ratios
• Assumes learners know the properties of equality

• This video is hosted on YouTube

Pros

• Works several problems involving proportions
• Contains a link to more proportion resources

Cons

• None

Common Core

7.RP.A.2.a MP6