Grade: 8 Subject: Science Unit: Scientific Modeling Lesson: 3 of 6 SAT: Information+Ideas ACT: Science

Guided Practice

Overview

Practice working with scientific models - understanding their purpose, identifying their limitations, and using them to make predictions.

Practice Problems

Question 1: What is the purpose of a scientific model?

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Answer: To represent complex systems or phenomena in a simplified way that aids understanding, explanation, and prediction

Models help us visualize things we can't directly observe (atoms, cells) or simplify complex systems (weather, ecosystems).

Question 2: Name three types of scientific models and give an example of each.

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Answer: Physical (globe), Mathematical (F=ma), Conceptual/Visual (food web diagram), Computer (climate simulations)

Different model types serve different purposes - physical models for visualization, mathematical for calculations, etc.

Question 3: A globe model of Earth doesn't show individual buildings. Is this a flaw?

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Answer: No - it's a necessary simplification; all models have limitations based on their purpose

The globe's purpose is to show continental positions and relative sizes, not building-level detail.

Question 4: The Bohr model shows electrons orbiting the nucleus in rings. How is this both useful and limited?

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Answer: Useful: shows energy levels, explains many phenomena. Limited: electrons are actually in probability clouds, not fixed orbits

The Bohr model is valuable for introductory understanding but doesn't capture quantum behavior.

Question 5: A food web model shows arrows pointing from prey to predator. What does the arrow actually represent?

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Answer: Energy flow - energy transfers from prey to predator when eaten

The arrow shows direction of energy transfer, not "who eats whom" (that would point the other way).

Question 6: Why do scientists sometimes use multiple models to represent the same thing?

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Answer: Different models highlight different aspects; no single model captures everything

Example: Wave model of light explains interference; particle model explains the photoelectric effect.

Question 7: A model predicts outcomes that don't match experimental results. What should happen?

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Answer: The model should be revised or replaced with a better one

Models are tools, not truth. When reality contradicts a model, we update the model.

Question 8: What makes a mathematical model like d = rt useful?

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Answer: It allows precise predictions and calculations, can be tested, and applies to many situations

Mathematical models provide quantitative predictions that can be verified experimentally.

Question 9: A student builds a model of the solar system with the Sun the size of a basketball. Why can't they show Earth at the correct scale?

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Answer: Earth would be about 0.2 mm across and 26 meters away - too small to see and too far to display

Scale models often can't show both size AND distance accurately. This limitation should be acknowledged.

Question 10: How can computer models simulate things we can't experiment with directly?

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Answer: They use mathematical equations to predict behavior of systems like climate, galaxies, or disease spread

Computer models allow "experiments" on systems too large, slow, or dangerous to study directly.