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Graphing Toad/Frog Respiration

By Lauren Jensen

Type of Activity:

  • Hands-on
  • Simulation
  • Inquiry lab
  • Authentic assessment
  • group/cooperative

Target Audience:

  • Life Science
  • Biology
  • Advanced Biology/AP Biology
  • Anatomy
  • Physiology

This activity helps the students answer:

  • Purpose of a control
  • The importance of care toward the experimental animal
  • The method of graphing the results


This is an activity which uses frogs or toads to demonstrate scientific method, by measuring the respiration rate, as well as the other external features of the live specimen. The kids enjoy working with the Arizona Toads.

Background Information

Notes for the teacher:

Scientific method seems to be a difficult concept to learn for high school students. During my prior years I have found that students are unable to grasp the purpose of a control in a scientific experiment. I have found a laboratory from heath Biology by Thompson and Braun, 1B Graphing Frog Respiration, which demonstrates the scientific method quite well. I have modified the laboratory to our agricultural area which is Yuma, Arizona near the Colorado River. The laboratory asks for live frogs to be used; I have the students catch Arizona toads in the early evenings around their homes. The stories of the toad hunts are interesting and enjoyable for myself and all of the students. The laboratory involves the study of the respiration of toads as their body temperature is adjusted to lower and higher temperatures. The temptation of the students to change the environment of the control is restrained and they begin to see the importance of having something to compare to. I have the students do this three day lab at the very beginning of the school year in the hopes of its motivational and assessment value of my new students.

The opportunity for the students to work with a living organism in a respectful manner is essential. I feel there are many objectives to this lesson and they range from: practice of accurate metric measurement of length, mass, and temperature; demonstrate the ability to make written observations of the behaviors of the toads; maintenance of the control toad; careful handling of the equipment; effective collecting and graphing of data. I also incorporate variables into the laboratory, for example, an active toad who will not stay in the container. I find it important to discuss with the students the obstacles encountered when working with live animals.

Initially, the students read about the Arizona toad and familiarize themselves with the anatomy of the toad. I make sure the students are aware of toad's parotid glands and the toxin released and what precautions the students are to take. I also make them aware of the toad's defense mechanisms (for example urinating and puffing up) so that the student will not injure the toad by accidentally dropping them. This activity gives the student an opportunity to see the difficulties of working with a live creature and acquire the skill of effectively handling the animal. If a student is uncomfortable about holding the animal, I ask that they record all observations and supervise the correct procedure of the laboratory. I have personally had a great deal of experience with veterinary science and I believe in respect of all living organisms.

Required of students:

Ability to accurately measure length, mass, temperature. They must be previously exposed to the importance of observations.

Preparation time:

A week. You need ample time to collect or order adult toads/frogs for each working group and a holding container that is at least two feet deep for your 30 toad/frogs (2 per group of two students).

Class time: Three days


  • Practice of accurate metric measurement of length, mass, and temperature
  • Demonstrate the ability to make written observations of the behaviors of the toads
  • Maintenance of the control toad
  • Careful handling of the equipment
  • Effective collecting and graphing of data


  • Scale (triple beam is the best for polishing student's skills)
  • Visible clock or timer
  • Source of crushed ice and warm water
  • Lab aprons
  • Goggles
  • Beakers for distributing the ice and warm water
Teams of Two should have:
  • Two amphibian enclosures with lids (approximately 12"x8"x9")
  • Two toads/frogs
  • Two thermometers
  • Graph paper
  • Data sheet for recording temperature change and respiration rates


Day 1:
  • Goggles and Apron are required.

  • You will work with a partner and pick up a toad and measure and record the following lengths: hindlimb, forelimb, nostril width. Measure the mass of your toad.

  • Locate the nostrils, and under the lower jaw of the toad. Every time the nostrils close the toad/frog has taken in a breath. You may rather use the toad/frogs underside of its lower jaw and see the movement inward and outward showing breathing.

  • Have your partner time you for one minute while you count the amount of times the toad/frog breathes. Repeat your timings five times and take an average. Record your data.

  • Once you have completed your data collection, return your toad/frog to its holding container, wash your hands with soap and water, wipe down the counter with a disinfectant, put away your goggles and aprons.

Day 2:

  • Today you will use two amphibian containers, a toad/frog in each, and fill the containers to the shoulders of the toads with tap water.

  • Record initial water temperatures and respiration rates five times in one minute intervals. Label one container, control, and the other experimental.

  • Once completed, begin to cool down the experiment toad by lowering the temperature of the water in increments of ten degrees. At each increment, record the toads respiration and any other behaviors. Do not alter the control's water temperature but measure its temperature and the respiration rate. Caution: Wait five minutes before you change the temperature of the water. You may drop the temperature no lower than 15 degrees Celsius.

  • Once at that temperature the students are then asked to warm the water gradually to the original temperature.

  • Your data table should be clear and understandable.

  • Be sure and return your toads/frogs to their holding container.Clean out the amphibian containers and put all equipment in its proper place. Be sure and clean your hands with soap and water.

Method of evaluation:

The students will graph the Temperature vs. Respiration rate. The students will arrange a report documenting the observation made and the completed graph of the before mentioned graph.


Goldfish can be used for this same lab as a comparison tool.

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