Question

canyon a - simulated rain 3 times weekly 100 ml of rain each time canyon b - simulated rain 3 times weekly 175 ml of rain each time to ensure that the investigation produces reliable data, what controls should the scientist put into place? a measurements of both canyons should be taken at the same time. b the canyon receiving more rain should start off taller than the canyon receiving less rain c canyon a should be made from a different material than canyon b. d the scientist should always pour the water into each canyon at the same speed e both canyons should have the same width at the beginning of the investigation

Explanation:

To ensure reliable data in an experiment (comparing two canyons' responses to rain), all other variables except the one being tested (rain amount) should be controlled. Controlling variables like canyon width (keeping them the same) ensures that differences in results are due to rain, not other factors. Option A: Measuring at the same time is about timing, not controlling canyon - related variables. Option B: Starting height difference introduces a new variable. Option C: Different materials for canyons introduces a variable. Option E (both canyons same width) controls the canyon's width, a key variable affecting erosion/response to rain.

Answer:

E. Both canyons should have the same width at the beginning of the experiment.