In 2005, the United States lost half of its coral reefs in the Caribbean in one massive bleaching event.1 When scientists first saw massive coral bleaching events around the world, they thought warming ocean temperatures might be causing the bleaching, but they needed to do more research to find the true cause. Because the scientists wanted to know about cause and effect, experimental design was the best tool for their research.

1) What are some other factors that might impact coral health that the researchers should consider?

excess trash in the ocean

warming water temperature

human interaction

water pollution

other ocean life

sunlight

movement of water

salinity

2) Write a research question about coral bleaching that can be answered using experimental design. You may consider the causes of bleaching, ways to prevent bleaching, or ways to reverse bleaching.

How does the pH level affect coral bleaching?

3) Design an experiment to answer your research question.

Part A: Identify the factors in your experiment.

Factor of interest - pH level

Response factor - amount of coral bleaching

Part B: Describe the set-up and procedure for your experiment. How will you change your factor of interest to create your experimental group? How will it be different in the control group? What other factors will need to be the same in both the experimental and control groups? How will you measure your response variable at the end of the experiment?

Experimental Group - change in the pH (increase)

Control Group - leave everything the same (pH level)

What factors need to be controlled - temperature, light, heat

How will you measure your response variable at the end of the experiment? - test the pH levels before and after the experiment and compare both groups.

How will you ensure that your results show the effects of your treatment and not other hidden causes - only really changing 1 thing and conducting the experiment multiple times.

Part C: What measures will you take to ensure your results show the effects of your treatment and not other hidden causes?

Why did you choose to design the experiment this way? - we chose this because it was easy to analyze and control.