Lesson 2.2: Skill 2, Scientific Reasoning and Problem-Solving

Introduction

In this lesson, students will learn about Skill 2 of the Four Scientific Inquiry and Reasoning Skills (SIRS) as defined by the AAMC for the MCAT. This skill involves applying scientific principles, theories, and models to novel situations, as well as combining multiple content areas within a single question. Mastery of this skill is essential for effectively answering the critical reasoning questions you will encounter in the MCAT’s science sections.

Learning Objectives

By the end of this lesson, students should be able to:

Apply principles, theories, and models to novel situations and evaluate explanations.
Combine multiple scientific content areas within a single question.
Apply a known principle to an unfamiliar scenario presented in a passage.
Evaluate competing scientific explanations and select the best-supported one.
Explain the main ideas and terminology behind Skill 2, Scientific Reasoning and Problem-Solving.

Scientific Reasoning: An Overview

Scientific reasoning is the ability to connect scientific knowledge with practical applications. This involves making judgments based on evidence, understanding patterns, and drawing conclusions that are consistent with scientific principles. Here, we will break down the essential components involved in scientific reasoning and problem-solving.

Fundamental Concepts

Principles and Theories: Every scientific discipline is built upon foundational principles and theories. For example, the laws of thermodynamics in physics or the theory of evolution in biology.
Models: Models are representations of systems that help in understanding complex concepts. For instance, the Bohr model of the atom helps visualize electron arrangements.
Evaluation of Explanations: In science, there are often multiple explanations for a phenomenon. Analyzing data and evidence to choose the best explanation is crucial.

Applying Principles and Theories

A key aspect of scientific reasoning involves applying known principles to new situations. Let’s explore how this is done with an example.

Example 1: Application of Newton’s Second Law

Scenario: A skateboarder of mass $m$ rolls down an inclined plane that makes an angle $\theta$ with the horizontal. Determine the acceleration of the skateboarder down the plane.

Known Principle: Newton's Second Law states that the force acting on an object is equal to the mass of that object multiplied by its acceleration, expressed as:

$$ F = ma $$

Where:

$F$ is the net force acting on the object,
$m$ is the mass of the object,
$a$ is the acceleration of the object.

Step 1: Identify all forces acting on the skateboarder.

Gravitational force: $F_g = mg$, acting downward.
Component of gravitational force along the incline: $F_{\parallel} = mg \sin(\theta)$.
Normal force: acts perpendicular to the incline, $F_N = mg \cos(\theta)$.

Step 2: Apply Newton’s Second Law.

$$ F_{\parallel} = ma $$

$$ mg \sin(\theta) = ma $$

Step 3: Solve for acceleration ($a$):

$$ a = g \sin(\theta) $$

Thus, the acceleration of the skateboarder down the incline is dependent on the angle of the incline and gravitational acceleration.

Competing Explanations

Often, scientific problems present multiple explanations or models which need to be analyzed for validity.

Example 2: Competing Theories of Disease Transmission

Scenario: In a class, two students propose different theories regarding the spread of a virus: one claims it is airborne while the other asserts it spreads through direct contact.

Step 1: Gather Evidence

Review available data related to the virus, such as routes of transmission studies and outbreak patterns.

Step 2: Evaluate Each Explanation

Analyze the conditions under which the virus spreads. Data might show that it can remain suspended in droplets in the air for several hours (supporting the airborne theory), while other data indicates high transmission rates in close-contact environments (supporting direct contact).

Step 3: Select the Best-Supported Explanation

Based on the preponderance of evidence available, you might deduce which mode of transmission plays a more significant role or if both contribute in different circumstances.

Integration of Knowledge Across Disciplines

Problem-solving often requires integration across different scientific fields. Let’s take a look at how chemistry and biology intersect in our understanding of a process.

Example 3: Photosynthesis

Scenario: Consider the process of photosynthesis, which can be approached from both a chemical and biological perspective.

Biological Aspect: In plants, photosynthesis occurs in chloroplasts and is responsible for converting light energy into chemical energy stored in glucose.

General equation of photosynthesis:

$$ 6CO_2 + 6H_2O \xrightarrow{\text{light}} C_6H_{12}O_6 + 6O_2 $$

Chemical Aspect: Understanding the reaction involves considering the energy transformations and chemical bonds involved.

The conversion of energy occurs as chlorophyll absorbs light energy, promoting electrons to higher energy states.

Integration: Being able to combine your knowledge of biology (the overall process of photosynthesis) with chemistry (the energy transformations involved) is essential for addressing questions that challenge you to apply interdisciplinary knowledge.

Conclusion

In this lesson, students has explored Skill 2: Scientific Reasoning and Problem-Solving. This involved applying principles, theories, and models to new scenarios, evaluating competing explanations, and integrating knowledge across scientific disciplines. Mastery of these skills is vital for success not only in the MCAT but in understanding and navigating real-world scientific challenges.

Study Notes

Scientific reasoning connects knowledge with practical applications.
Key concepts: principles and theories, models, evaluation of explanations.
Newton’s Second Law ($F = ma$) is foundational in physics.
Scientific problems often have multiple explanations that need evidence-based evaluation.
Integration of knowledge is critical for comprehensive understanding in science.