Nature of science activity from Randy Bell's book. (can with ropes)

Create a model. Observe behavior that contradicts the model. Change the model. This is how science works.

How does this apply to nanoscience?

Students have been taught models for properties of materials. Specifically, students have been taught that certain properties, called intensive, do not change. This rule does not hold at the nanoscale. Therefore, the model for properties of matter must be modified.

Intensive properties are defined as properties that do not depend on the amount of matter present. Intensive properties include: color, odor, luster, malleability, ductility, conductivity, hardness, melting/freezing point, boiling point, and density.

The concept of intensive properties is only valid in the macroscale world. At smaller scales, these properties change.
http://www.wisc-online.com/objects/ViewObject.aspx?ID=GCH8204 Activity that illustrates differences in intensive properties of gold.
http://www.accessnano.org/teaching-modules/gold Activity that explains the uses and property changes in gold from the macroscale to the nanoscale.

The novel, often unexpected, properties that matter exhibits at the nanoscale are forcing scientists and engineers to change their models for explaining the structure and behavior of matter. (Stevens, Sutherland, & Kracjik, 2009)

The intensive and extensive properties of matter that students learn are useful for comparing materials and predicting behavior in the macroscale world. However, these rules do not apply at the atomic scale.
Properties that were thought to be invariant for matter change at the atomic scale. Categorizations of properties must be linked to scale.

Suggestion: In Lesson 2, Intro to nanoscience, present students with a situation where properties that are called "intensive" are different. Why are they different? How can we adjust our model for the properties of matter?

This ties in to Big Idea 8 (Steven, Sutherland, Kracjik, 2009). "Scientists use models and simulations to help them visualize, explain, predict, and hypothesize about the structures, properties, and behaviors of phenomena (eg. objects, materials, processes, systems.) The extremely small size and complexity of nanoscale targets make models and simulations useful for the study and design of nanoscale phenomena." p. 58

What kind of models are used in science?
  • physical
  • computer-based
  • static
  • dynamic
  • equations
What are the characteristics of a good model?
  • describes, explains, predicts aspects and behaviors of a target
  • compromise between how much explanatory power and model complexity
  • helps to visualize what cannot be seen
    • too large or small
    • too fast or slow
    • potentially dangerous to try
    • too costly
  • models are constantly reevaluated according to new scientific evidence
Simulations are representations of models.
Building and refining models are an important part of science.

NSES (1996) "scientists formulate and test their explanations of nature using observation, experiments, and theoretical and mathematical models." p.171