Science Assessment ~ Topics ~ Matter and Energy in Living Systems ~ Item ME031003 ~ Student Performance

A student is growing broccoli in his garden. The broccoli head is the part of the broccoli plant that humans usually eat. When the broccoli first started growing, the broccoli head was only about an inch wide. A few weeks later, it had grown to be as large as the broccoli heads you usually see in the grocery store.

Young broccoli. Photo (CC) by InsipireKelly on Flickr.

Fully-grown broccoli. Photo(CC) by Yogita Mehra on Flickr.

What explains how the broccoli head got so much bigger?

The broccoli plant took in a lot of minerals from the soil and added them to the growing broccoli head.
The broccoli plant took in a lot of water, which caused the existing cells in the broccoli head to get bigger.
The broccoli plant made glucose molecules from molecules it took in and used the glucose to make larger molecules that became part of the growing broccoli head.
The broccoli plant’s cells were dividing all the time to increase the number of cells and no additional matter was needed.

Pre-Test

Distribution of responses
Answer Choice	Overall	Grades		Gender		Primary Language
	n = 374	6–8 n = 374	9–12 n = 0	Male n = 206	Female n = 168	English n = 346	Other n = 28
A.	31%	31%	NAN%	30%	32%	31%	32%
B.	14%	14%	NAN%	17%	10%	13%	21%
C.	41%	41%	NAN%	38%	45%	42%	29%
D.	14%	14%	NAN%	15%	13%	14%	18%

Post-Test

Distribution of responses
Answer Choice	Overall	Grades		Gender		Primary Language
	n = 378	6–8 n = 378	9–12 n = 0	Male n = 207	Female n = 171	English n = 350	Other n = 28
A.	25%	25%	NAN%	27%	22%	24%	32%
B.	8%	8%	NAN%	8%	9%	8%	7%
C.	64%	64%	NAN%	63%	65%	64%	57%
D.	3%	3%	NAN%	3%	4%	3%	4%

Science Assessment

Item ME031003: A growing broccoli head gets bigger by taking in molecules, using them to make glucose, and using the glucose to make larger molecules that become part of the plant’s body.

Pre-Test

Post-Test