Activity 3: Diffusion of Color Through Water (Continued)

What effect do water temperature, barriers, and concentration have on diffusion?

 

  1. Using the time steps and grid size determined in Activity 2, divide the class into four groups.
  2. Each group will explore a different variable, with one group acting as a control group.

     

  3. All temperatures are in Celsius and may be approximated.

     

  4. Each group will use 3 drops of food coloring for each trial.

     

Click on any of the links for a breakdown of the variables for each group.

 

Group A: Control Group

Group B: Change in Temperature

Group C: Change in Salt Water Concentrations

Group D: Adding Barriers

 

Teaching Strategies

This activity can be used for a final assessment for the understanding of diffusion and experimental design.  Students should be encouraged to complete this activity with little to no instruction from the teacher.  The teacher should present the challenge:  Design an experiment to document the diffusion of food coloring under varying conditions of temperature, salt water concentrations, and with additional geographic barriers.  Students should begin their work in four teams and then move the control groups to share their data with their respective experimental groups.  A complete report of the team findings and a poster presentation will complete the assignment. 

The teacher should make available the flat bottomed pans, modeling clay, stopwatches, salt, food coloring, dry and liquid measuring tools, and a hot plate for warming water.  More of the acetate gridded sheets should be available.  Students should be encouraged to design the best experiment possible and to ask for additional materials if needed.  These requests should be reasonable.  For example students may ask to use the video camera in their experiment.  Where possible fulfill their needs to encourage them to move beyond what has already been used.  All requests should fall within safe experimentation conditions. 

A regular lab report grading rubric could be used, but be sure to add specific items that relate to the visualization of data.  Students at this point have used flip books, graph paper diagrams, graphs, and electronic surface plots.  By including scored parameters up front, you will receive higher quality reports and presentations.  Set your standards high and help your students to meet them.

For example:

Section Descriptor 0 1 2 3 4
Introduction to Experimental Purpose and Method
  • Title section is complete.
  • Clear and appropriate purpose or hypothesis.
  • Procedure included as list, flowchart, or diagram of method.
          
Documentation of Experimental Results
  • Data and observations properly recorded with units and labels present in table headings.
  • Diagrams are used where necessary to explain data.
          
Data Analysis

Visualization of Data
  • Graphs are accurately constructed with axis labels and units.
  • Visuals [graphs] accurately represent the data.
  • Computer generated diagrams clearly show computer simulations or represent physical models.
          
Explanation/Conclusion
  • Concluding statements are in paragraph form and major findings are cited in support of described relationships. 
  • Concluding discussion questions are addressed thoroughly.
          
Presentation
  • Lab is neatly written or typed with proper grammar and no spelling errors
  • Report is on time.
  • Presentation  included computer-generated and/or hand made visuals  and was presented with multimedia software that enhanced the presentation.
         

Return to Diffusion Module

Return to Warm-up Activity

Return to Activity 1

Return to Activity 2