A student wanted to see if the color of water impacted the increase in temperature, in degrees Celsius (°C), after 30 minutes in the Sun. Three
beakers were filled with 50 milliliters (ml) of water, and five drops of food
coloring were added to each beaker. The beakers were then placed on a
window ledge in direct sunlight and temperature readings were recorded
every 10 minutes for 30 minutes. What was the test (independent) variable
in this experiment?