Module 6: Content Specific Guidelines
What is in this module?
Overview
For each of the topics we evaluate videos for, we develop a set of specific guidelines that address the expectations for how a video would likely meet the certain criteria. We also identify any common issues to be on the lookout for. It should be noted that we do not claim that our articulations for casual mechanistic reasoning or disciplinary core ideas are the only way to meet these criteria. If you feel that a video meets the criteria, but perhaps address a different core idea or provide an explanation for another question, that is great.
The following content provide a specific example for how this framework was adapted for videos focused on Le Chatelier’s Principle (LCP). You can see how the specifics for other topics on the Content Info Pages.
Johnstone's Triangle elements
| Element | Examples |
|---|---|
| Macroscopic | General Definition for Macro: things we can see (observations) OR specific measurements. Visible phenomena - most common ones involve things that change color. For example, cobalt chloride equilibrium systm (blue to pink) or N2O4 to 2NO2 system (brown vs. colorless). This can be a video/pictures of the system or a simulation. |
| Symbolic | General Definition for Symbolic: standardized, discipline-specific short-form representations that efficiently communicate significant information. It is a universal shorthand that bridges the macroscopic and particulate levels. Most common is a chemical equation of the equilibrium system, but some videos show a graph of change of concentrations of reactions and products as the reaction proceeds. |
| Particulate | General Definition for Particulate: visual model that helps “visualize” arrangement, movement, interaction, or composition of matter as it relates to the concept of interest. This tends to be the least common element included in LCP videos. Particle representations should show reactants and products going back and forth. Particles sitting on a balance does NOT meet this criteria. Particles do not have to be in motion (dynamic) but they do have to be connected to the main concept, in this case equilibrium and LCP. |
| Connection between levels | Videos should make explicit connections between two or more levels for this to be coded as present. For example, they could show a particle level diagram of how reactants are converted to products and then the reverse reactions and connect that how the concentrations are changing on a concentration vs. time graph. |
Chemistry Core Ideas
For most topics there are multiple core ideas that can and arguably should be addressed for a deep conceptual understanding of the topic. For LCP, we anticipate videos addressing one or more of the following.
| Core Idea Elements |
|---|
| Change and Stability in Chemical Systems | Energy | Particulate Nature of Matter |
|---|---|---|
|
Change: "Stressing" an equilibrium system (changing concentrations or temperature) causes changes in relative rates of the forward and reverse reactions. Return to Stability: The system "shifts to offset the stress" as an equilibrium system returns to a state where the forward and reverse reactions are equal. Must have both parts |
Changing the temperature causes a shift in an equilibrium by altering the number of collisions that are “successful” in overcoming the activation energy barrier for the reaction. Due to the differences in the activation energy barriers for the forward and reverse reactions, the two processes will be differentially impacted, leading to changes in the relative concentrations of the reactants and products. |
Stresses on the system will alter the rates of the forward and reverse reactions by changing the number of collisions or the number of successful collisions. |
Science Practices
We anticipate that the most likely Science Practices you encounter will be:
Constructing Explanations and Engaging in Argument from Evidence
|
Developing and Using Models
|
Analyzing and Interpreting Data
|
Using Mathematics and Computational Thinking
|
Casual Mechanistic Reasoning
Must have both How and Why?
Option 1: What causes changes to a system in equilibium?
How:
- Collisions between molecules lead to forward and reverse reactions occurring.
- Changes in concentration or temp alter the relative rate of success of collisions to lead to the forward or reverse reaction. (Level below the process of interest)
Why:
- Changes in concentration or temp alter the relative forward and reverse reaction rates.
- If rates are unequal, then the rate of one will increase and the other decrease (due to changing concentrations of reactants and products) until they become equal.
Both parts must be present for a complete causal mechanistic explanation.
Multimedia Principles
Multimedia learning as knowledge construction: The goal of multimedia presentations is not only to present information but also to provide guidance for how to process the presented information – that is, for determining what to pay attention to, how to mentally organize it, and how to relate it to prior knowledge. We will categorize the videos along each of the following criteria (High and Low should be mutually exclusive.)
| High | Low |
|---|---|
|
|
Common Issues
- Some videos treat equilibrium systems more as steady state than equilibrium
- Example, a hole in the ground staying the same size because someone is shoveling dirt out as fast as another person is shoveling dirt in is steady state (equal rates of things going in and out) as opposed to equilibrium (equal rates of things going back and forth)
- Particles on a balance
- Some videos put particles on a balance to show equilibrium and then when you add more to one side the systems is out of balance. This is problematic as at equilibrium the concentrations of reactants and products (or the masses of reactants and products) are rarely if ever equal!
- LCP as an algorithm
- Frequently, LCP is treated as an algorithm, e.g., if you increase a reactant the equilibrium shifts to decrease the reactant. Though this is not incorrect, it does not explain how or why the equilibrium shifts when you increase that concentration.