Science Assessment ~ Topics ~ Control of Variables ~ Item CV021003 ~ Student Performance

A farmer wants to find out which type of soil is best for growing his corn. He also wants to find out which type of fertilizer is best for growing his corn.

He does the following experiment using two different types of soil and two different types of fertilizer:

What can the farmer conclude from this experiment?

He can conclude that Soil B is the best soil for growing his corn.
He can conclude that Fertilizer Y is the best fertilizer for growing his corn.
He can conclude that Soil B is the best soil for growing his corn and that Fertilizer Y is the best fertilizer for growing his corn.
It is NOT possible to conclude from this experiment which soil is best for growing his corn or which fertilizer is best for growing his corn.

Distribution of responses
Answer Choice		Overall	Grades		Gender		Primary Language
		n = 2498	6–8 n = 1419	9–12 n = 1070	Male n = 1227	Female n = 1232	English n = 2143	Other n = 291
A.	He can conclude that Soil B is the best soil for growing his corn.	15%	19%	11%	17%	13%	15%	19%
B.	He can conclude that Fertilizer Y is the best fertilizer for growing his corn.	9%	10%	8%	10%	8%	9%	13%
C.	He can conclude that Soil B is the best soil for growing his corn and that Fertilizer Y is the best fertilizer for growing his corn.	48%	53%	43%	45%	52%	49%	48%
D.	It is NOT possible to conclude from this experiment which soil is best for growing his corn or which fertilizer is best for growing his corn.	27%	18%	39%	27%	26%	28%	20%

Science Assessment

Item CV021003: In an experiment on the effect of temperature and soil type on the growth of corn plants, with both variables changing at the same time, no conclusion can be reached regarding the effect of either temperature or soil type on the growth of the plants.