Measure of pH using Vernier Probes

By: Mike O'Donnell



Students will work in groups of two to measure pH of freshwater system when crayfish are present in water sample. A control will be set-up and the biology of the crayfish will studied. The pH should increase as the crayfish releases ammonia as a waste product. (Ammonia is a base)

Keywords: Crayfish, ammonia levels, scientific method, freshwater biology, ecosystems.


Students collect information about feshwater systems and crayfish.
Students will design, plan, and organize a experimental project.
Students will learn the use of technology(vernier probes)for data collection
Once the data is collected, students will analyze the data and draw conclusions.
Students will present the data to the class.


1. Define a problem based on a specific body of knowledge, for example: biology, chemistry, physics, and earth/space science, and do the following:
1. pose questions about the natural world,
2. conduct systematic observations,
3. examine books and other sources of information to see what is already known,
4. review what is known in light of empirical evidence,
5. plan investigations,
6. use tools to gather, analyze, and interpret data (graphical representations of data, including data tables and graphs),
7. pose answers, explanations, or descriptions of events,
8. generate explanations that explicate or describe natural phenomena (inferences),
9. use appropriate evidence and reasoning to justify these explanations to others,
10. communicate results of scientific investigations, and
11. evaluate the merits of the explanations produced by others.


Academic Preparation

Material Needed:
1. Internet/computer for research
2. vernier probes
3. culture dish and freshwater and crayfish
4. Text: identifying kidney function and waste
5. Presentation Power point of Flip camera


1. Reading assignment: Crayfish and crawdads
2. Chemistry notes pH acids and bases and ammonia
3. Use of the vernier probes pH collect data as you blow bubbles into a cup of water (CO2 will convert to carbonic acid and the pH will drop)
4. Design an experiment to measure changes in pH of when a crayfish is placed in a culture dish of 500ml of freshwater.
save and analyze the data. draw a conclusion.
5 Create and present a 6 slide presentation of 5-6 minute (Flip) video of the project. (include background, puropose, procedure, data collection, errors, Conclusion)
6. Processing form: Summarize each presentation Good, work i=ons, and What I learned)


Quality of research
Experimental design
Processing form
Standardized test Scientific method pre and post test

Extensions and Adaptations

Use within the Nitrogen Cycle

Estimated Lesson Duration

3hr 00min


  • Glencoe Science Biology "the Dynamics of Life"
  • Carlina biological Crayfish tips (vol 66 No 1 Winter 2003)