Convert a geological model interval

Supplied materials

• All measurements and observations below are supplied classroom examples. They are not data from actual learners or a claim about a particular real site.
• Paper or browser document; an ordinary calculator is optional.
• Rule: Years equal supplied million years multiplied by one million. Formula: a*1000000. Variable key: a = interval (million years)
• Distinct worked inputs and result: A distinct interval of 1.5 million years equals 1,500,000 years.
• Assessment case 1: Supplied case 1: interval (million years)=2, using the explicitly named quantities. Years equal supplied million years multiplied by one million. What result follows?
• Assessment case 2: Supplied case 2: interval (million years)=3.5, using the explicitly named quantities. Years equal supplied million years multiplied by one million. What result follows?
• Assessment case 3: Supplied case 3: interval (million years)=6, using the explicitly named quantities. Years equal supplied million years multiplied by one million. What result follows?
• Assessment case 4: Supplied case 4: interval (million years)=8.2, using the explicitly named quantities. Years equal supplied million years multiplied by one million. What result follows?
• Assessment case 5: Supplied case 5: interval (million years)=12, using the explicitly named quantities. Years equal supplied million years multiplied by one million. What result follows?
• Assessment case 6: Supplied case 6: interval (million years)=15.4, using the explicitly named quantities. Years equal supplied million years multiplied by one million. What result follows?

Learn the idea

Unit conversion changes the number used to express an interval, not the interval itself. The supplied values are fictional ages, not dates for named fossils or events.

Years equal supplied million years multiplied by one million. The formula in the supplied model is a*1000000. Variable key: a = interval (million years). Million means one million. Do not confuse thousand and million.

A distinct interval of 1.5 million years equals 1,500,000 years. A conversion is not an independent dating measurement. Track the quantity and unit before calculating. Explain the meaning of a positive, negative or fractional result when relevant. A numerical answer supports the stated model calculation; broader claims require the additional measurements and assumptions described here.

1. Name the measured quantities and their units before substituting values.
2. Write the stated rule and use the variable key to match each symbol to its explicitly named quantity.
3. Calculate each supplied case separately, keeping intermediate arithmetic and the result unit.
4. Explain the result in context and identify the assumption that would invalidate direct use of the rule.

Check your reasoning

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Take it further

Changed-input task: use the same stated model with interval (million years)=3. Expected result: 3000000 years. Explain what changes and keep this assumption: A conversion is not an independent dating measurement.

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