Victory for the ACT Student Text 15e

L ESSON 2 | R ESEARCH S UMMARY • 311 Should the investigator have used different soil types in each sandbox experiment? A. Yes, because different soils may erode differently. B. Yes, because a different group of plants could have been used in each sandbox as well. C. No, because some soils can be washed completely away within the two-week experiment. D. No, because the soil type was a controlled variable in all three experiments. ƒ†„‘š ͵ •’‡…‹ϐ‹…ƒŽŽ› †‡‘•–”ƒ–‡• –Š‡ role of which particular variable in the set of experiments? F. Rain G. Wind H. Gravity J. Temperature If another sandbox were set up, which of the following conditions would probably cause wider and deeper channels in the soil of the new sandbox than those in Sandbox 3? I. Steeper angles for the sandbox II. A greater volume of water during the 15-minute showers every twelve hours III. Removal of plants from soil A. I only B. I and II only C. II and III only D. I, II, and III

12. Results from all three sandboxes indicate that: F. different types of soils and rocks are affected differently by environmental factors. G. under all tested conditions, plants reduce erosion. H. changing wind and temperature conditions can affect erosion patterns. J. water from short periods of rain has little or no effect on erosion patterns. 13. The experimental design and results do NOT support which of the following claims? A. Light winds have no erosive effect. B. Slopes have more erosion than level surfaces. C. Water has major erosive effects. D. The effects of changing temperature remain unanswered. Sudden cloudbursts are known to cause more erosion than longer periods of mild rains. How could the present experiments be changed to examine this idea? F. Raise the angle in Sandbox 3 to produce a steeper slope. G. Add the “rain conditions” from Sandbox 2 to the conditions in Sandbox 1. H. Include light, 15-minute showers every 6 hours instead of every 12 hours. J. Every 12 hours, allow the same total volume of water to fall in a 5-minute span rather than in a 15-minute span. 14.

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