[Plant-education] Three plant articles in Feb. 2006 American
David R. Hershey
dh321 at excite.com
Tue Mar 7 18:50:29 EST 2006
The February, 2006, American Biology Teacher has three plant articles,
all by science educators. They may be interesting reading for members
of this group because they offer a different perspective. Each has the
now-required discussion of the National Science Education Standards.
Case (2006) promoted student research that determined leaf stomatal
index using the nail polish, scotch tape technique. As a plant
educator, I would have also required students to calculate the
stomatal density so they knew how to determine the size of the
microscope's field of view. Case mentioned that stomatal density was as
high as 58,140 stomata per square cm on the lower surface of black oak
leaves. However, Yocum (1935) reported 103,800 stomata per square cm on
the lower surface of scarlet oak (Quercus coccinea) leaves. Yocum noted
that only Veronica cookiana was reported to have a higher stomatal
density at 220,000 per square cm. The 58,140 figure seemed to be
Yocum's datum although he reported just 580 stomata per square mm or
58,000 per square cm for black oak. I wonder where the extra 140 came
Barman et al. (2006) studied plant misconceptions held by over 2,400
students in grades K-8. In one part of the study, teachers showed their
students 12 pictures and asked "Is this a plant or not a plant?" Eighty
percent or more said yes for pictures of a flower, grass, bush, fern,
oak tree, and pine tree. Only about half or less answered yes for seeds
and just 3 to 6% answered yes for a telephone pole. One wonders if the
students were aware that most telephone poles are made from trees.
When Barman et al. (2006) provided a 12-item list and asked grade 6-8
students "Do plants need this to grow?" Water (99%), sun (99%), potting
soil (83%), air (83%), plant food (69%) and carbon dioxide (65%) were
the top six answers. Student hydroponic experiments or experiments with
aquatic plants, such as duckweed, would be a simple way to address the
misconception that potting soil was required for plant growth.
Barman et al. (2006) listed several of the same plant misconceptions as
my lists (Hershey 2004, 2005) including problems with the misnomer
"plant food." The sad thing is that my lists of plant misconceptions
were compiled from the biology teaching literature written by adult
authors with college degrees, not the K-8 students inteviewed for
Barman et al. (2006). Some of the student misconceptions about plants
are probably obtained from the error-filled teaching literature.
Kranz and Barrow (2006) provided an interesting extension of Barman et
al. (2006) by listing some plant misconceptions held by college
students studying to be elementary school teachers. Their
misconceptions included that "enamel covers the seed" and that plants
were not alive because they lacked DNA and did not respond to stimuli.
David R. Hershey
Barman, C.R., Stein, M., McNair, S. and Barman, N.S. 2006. Student's
ideas about plants & plant growth. American Biology Teacher 68: 73-79.
Case, S.B. 2006. Leaf stomata as bioindicators: Stimulating student
research. American Biology Teacher 68: 88-91.
Hershey, D.R. 2004. Avoid misconceptions when teaching about plants.
Hershey, D.R. 2005. More misconceptions to avoid when teaching about
Kranz, P.D. and Barrow, L.H. 2006. Inquiry with seeds to meet the
science education standards. American Biology Teacher 68: 92-97.
Yocum, L.E. 1935. The stomata and transpiration of oaks. Plant
Physiology 10: 795-801.
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