Lesson: Does Size Matter?

Author: Eric Kolb

Area: Physical Sciences

Grade Level: 7-8

Overview:

When comparing two different solutes in equal percent-by-weight solutions, the relative sizes of the solute molecules will determine the concentration of solute molecules in a given volume such that a larger solute molecule (thus larger mass) will result in a more diluted concentration-by-volume solution. In this lesson, students will explore this relationship in three related experiments.

Standards:

AZ State Science Standards:
Standard 1: Science as Inquiry

1SC-E1. Identify a question, formulate a hypothesis, control and manipulate variables, devise experiments, predict outcomes, compare and analyze results, and defend conclusions
• Conduct an experiment using a scientific method
• Analyze the results of an experiment
• Defend conclusions drawn from the analysis

1SC-E2. Create a model (e.g., a computer simulation, a stream table) to predict change
• Construct a model that demonstrates change within a system
• Describe variables that cause change
• Explain cause and effect of variables within a system

1SC-E3. Organize and present data gathered from their own experiences, using appropriate mathematical analyses and graphical representations
• Construct a representation of data (e.g., histogram, stem-and-leaf plot, scatter plot, circle graph, flow chart)
• Interpret patterns in collected data

Standard 5: Physical Science

5SC-E1. Examine, describe, compare, measure, and classify objects and mixtures of substances based on common physical and chemical properties (e.g., states of matter, mass, volume, electrical charge, density, boiling points, pH, magnetism, solubility)
• Classify objects and mixtures of substances based on physical and chemical properties
• Analyze physical and chemical properties of objects and mixtures

			Percent-By-Weight, Solutes, Molecule, Concentration