## Reflection: Complex Tasks History of Earth: Part 1: Follow up - Section 6: Independent Work

At some point in planning, all teachers are faced with the depth decision.  I think this is especially difficult for middle school teachers who may be dying to go on to more advanced (and interesting) content.  We all have to have a firm understanding of where the complexity is in the unit and whether it is appropriate.

Last year I decided that I wanted students to be able to calculate their own ratios for timelines.  I spent days going over setting up ratio proportions and solving through cross multiplication.  At the end of the unit I was able to measure two things.

1) Most of my students were still confused about ratios and still couldn't do them independently.

2) Understanding ratios did not seem to make it more likely that they would have more insight into the history of Earth.

Because of this, I decided to skip the ratios this year and instead concentrate on some of the more important conceptual learning.

• Earth's history is enormously long.
• Life on Earth was simple for an enormously long time.
• Geological events can effect the evolution of life.

I know that some teachers might look at this and think that I am losing an opportunity for depth and complexity.  But really, I don't think ratios are that complex or rigorous.  I think they're just hard.  I'd rather make the math easier and the science thinking more complex.

The Depth Decision

# History of Earth: Part 1: Follow up

Unit 12: History of Earth: Part 1
Lesson 4 of 7

## Big Idea: Plants. Fish. Amphibians. Reptiles. Disaster.

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### Andrea Pless

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