Goldfish Breathing (Respiration) Investigation LAB INSTRUCTIONS – DO NOT WRITE ON THESE PAGES Question: How does water temperature affect goldfish breathing rates? Prediction (Hypothesis): Write your prediction on your Student Lab Sheet. Materials: Lab Instructions and Student Lab Sheet 250 mL Beaker 1 Waterproof thermometer 1 Goldfish 1 net for moving goldfish 1 stopwatch or timer Bucket of small gumdrop-­‐sized ice cubes (9 cubes per team) Procedure: 1. Fill the beaker to the 150 mL line (just over half) with water from the fish tub or the spring water container. 2. Place a thermometer inside the beaker so it rests along one edge. Be sure you can read the thermometer. 3. Using a net, carefully remove the fish from the main tub and put it in the cup. 4. Wait 2 minutes to let the fish adjust to its new environment. 5. Read the temperature and record the measurement (°C) on your data table. 6. Set a timer for 30 seconds. 7. Start the timer and begin counting the number of times the fish’s operculum moves out and in. Record this measurement for Trial 1 on your data table. 8. Repeat for Trials 2 and 3 (for a total of 3 times). Calculate the average number of breaths. 9. Add 3 small ice cubes (small gumdrop-­‐sized) to the cup. 10. Gently stir the ice at the top of the cup with the thermometer. 11. Once the ice is melted, stir the beaker again gently. Be careful to avoid the fish and thermometer. 12. Wait 1 minute. 13. Set a timer for 30 seconds. 14. Start the timer and begin counting the number of times the fish’s operculum goes out and in. Record this measurement for Trial 1 for +3 Ice Cubes. 15. Repeat for Trials 2 and 3 (for a total of 3 times). Calculate the average number of breaths. 16. Add 3 additional ice cubes (for a total of 6) and follow steps 10 – 15 and record your data for +6 Ice Cubes. 17. Add 3 more ice cubes (for a total of 9) and follow steps 10 – 15 again and record your data for +9 Ice Cubes. 18. Once you have completed the temperature readings, allow the water in the cup to return to room temperature before placing the goldfish back in its original tank. Stop and Think About Your Investigation (and answer these questions on your lab sheet): What is the MANIPULATED VARIABLE? (What are you changing or comparing?) What is the RESPONDING VARIABLE? (What are you measuring or collecting?) What are the CONTROLLED VARIABLES? (What should you keep the same?) Data: Write your data on your Student Lab Sheet. Number of Breaths Taken at Different Water Temperatures Number of Breaths in 30 Seconds Average Actual Number of Temperature Trial #1 Trial #2 Trial #3 Breaths Room Temperature +3 Total Ice Cubes +6 Total Ice Cubes +9 Total Ice Cubes Data Analysis (Graph, Chart, etc.): Create a line graph of your data on the Student Lab Sheet. 1. Write the name of the RESPONDING VARIABLE (what you are measuring) along the left side of the graph. Be sure to include the units. 2. Then look at your data (the number of breaths) and determine the best numbers to use along the left side (from the top to the bottom). Use the thicker lines to represent multiples of 5 (5, 10, 15, 20, etc.). 3. Label the bottom of the graph the MANIPULATED VARIABLE (what you are changing). Include the units. Number of Fish Breaths Taken at Different Water Temperatures (°C) Responding Variable = 0°
5°
Manipulated Variable = 10°
15°
20°
25°
Data Analysis (continued) – Discuss these questions with your team/the class: 1. Was your prediction at the beginning of the lab correct or incorrect? 2. Describe how the fish’s breathing rate changes with temperature. 3. What might be a reason the breathing rate changed this way? 4. What factors (besides temperature) might have affected the fish’s breathing rate? 5. Was the class average similar to your fish data? Why do we take an average? Conclusion: In your conclusion, be sure to: 1. Answer the experimental question: For example, you could write something like: As the_______ decreased or increased, the_______ decreased or increased.
(manipulated variable= (choose water temperature) one) (responding variable= number of breaths per 30 seconds) 2. Include supporting data for the lowest and highest conditions. In other words, write several sentences that describe what happed to the fish’s breathing rate at the different temperatures – especially at the lowest temperature and highest temperature. BE SURE TO INCLUDE NUMBERS! For example, you could write something like: When the water temperature was ____
(lowest temperature),
the number of
breaths per 30 seconds was __________(the number of breaths at that temperature).
However, when the water temperature was ____
(highest temperature),
the number
of breaths per 30 seconds was __________(the number of breaths at that temperature).
3. Use explanatory language and describe how all of the data is connected. In other words, summarize what your data means and use “juicy” words throughout your conclusion. As a summary, you could write something like: So, as the water temperature changes by ___° the fish breathing rate goes
(up or down) by ___ breaths per 30 seconds. This data supports or does not
support my hypothesis.
(choose one)