Students dissect sheep brains
November 6, 2008
By Laura Geggel
Sheep brains are no larger than the hand of a middle-school student, but they held the attention of Kyle Wallace’s eighth-grade biology class for well over an hour.
“It feels like a dog toy,” Courtenay Wilhelm said, as she probed the neural matter with her forefinger.
Students in Wallace’s three biology classes picked up the scalpel Oct. 29 for a lab relating to their neurology unit. The teenagers had already learned the names for the brain’s regions — ventral, caudal, dorsal and rostral — through lessons and homework. The lab helped students connect the unit’s vocabulary to the sheep specimen.
“This is a great real-life application,” Wallace said.
After reviewing lab etiquette, the class trooped across the hall to the laboratory in the North Fork of Twin Falls Middle School. Students fished sheep brains — each duo receiving half a brain — from a bucket and immediately began following a worksheet detailing the dissection steps.
First, students transcribed five physical characteristics relating to the brain.
“It looks yellowish,” Kaylie Duran said.
Another student, Sarah Montgomery, noted how the stringy and purple blood vessels were embedded in the grey matter.
The brain’s “soft and squishy” composition didn’t surprise Mountgomery. It made sense, “or else you wouldn’t have such a hard head to protect it,” she said.
Students jotted down functions pertaining to each lobe they could identify. The frontal lobe helps store certain kinds of long-term memory, they wrote. The temporal lobe helps with speech, memory and hearing.
Wallace just started teaching his students about neurons, and Alex McAlistair took a stab at explaining their function.
“It’s like the cell that sends messages throughout the body telling the body to do stuff,” McAlistair said, consulting her notebook briefly.
Next week, Wallace said he would review neurons in more depth and explain the function of the corpus callosum — the structure that allows chatter between the brain’s two hemispheres.
This is the third year the eighth grade has dissected sheep brains. Some of the worksheet’s questions asked students to compare the sheep brain to its human counterpart.
Once biology classes move into their next unit — systems of the body — they will dissect a frog.
“The brain is your control center. Well, what is it controlling?” Wallace asked, explaining the logic behind the frog lab. The last dissection of the year — a cow’s eye — will show students a specific system.
Students said they enjoyed the hands-on aspect of the dissection lab.
“Instead of reading what other people have seen, you can learn it for yourself,” Josephine Cousins said.
“I liked exploring the cerebellum,” Lydia Pinkley said, adding that the cerebellum controls balance and coordination, the exact skills she needed to slice the brain in two with the scalpel. “You actually get to touch it.”
Some questions on the worksheet pushed the students to consider the brain’s origin.
“What kinds of things does a sheep need to remember?” read one question after students removed the C-shaped hippocampus, the structure storing short-term memory.
Aren Orr said he and his classmates had reviewed ethical considerations of the lab.
“We went over to respect it because it once was a living animal,” Orr said.
The lab helped students grasp the material, but funds are tight for biology classes. Twin Falls has no microscopes or Bunsen burners and they had to borrow dissection trays from Snoqualmie Middle School. In the past, the Snoqualmie Valley Schools Foundation funded the brain bill, but this year the department paid $800 for the 60 brain hemispheres.
Rhonda Hughes, who assembles science kits for the district, said much of the funding responsibility falls on the foundation and the PTSA.
Middle-school dissections prepare students for high school anatomy lessons. Students in anatomy and physiology and AP biology can dissect a fetal pig.
“If you’re trying to understand the structure and function, dissections are one way to explain to a student that relationship,” said Andrew Rapin, Mount Si High School AP biology teacher.