Bonnie Chen teaches ninth grade honors biology at Belmont High
School in Belmont, Massachusetts. Located just outside of Boston and Cambridge, Belmont
High School draws students from a range of communities in the Boston area. Roughly 25
percent of the students come from homes where at least one parent is a scientist, doctor,
or researcher. Close to half of the students at Belmont High School take two science
classes in a given year. Advanced Placement courses are offered in physics, chemistry,
biology, and environmental science. Massachusetts' frameworks for teaching science direct
curriculum topics, but teachers are free to set the order, plan how they will teach, and
Ms. Chen began the year with an introduction to scientific understanding
and an overview of evolution as a unifying theme in biology. In an evolution discovery lab
students practiced putting skull and skeleton collections in chronological order and
looking for similarities in vertebrates.
By the time Ms. Chen's students began the bird beak experiment, they'd
covered several units in biology: the scientific method, inorganic and organic chemistry,
and cell biology. Just prior to the lesson, students learned general information about
DNA, chromosomes, transcription and translation, and types of gene mutations and
chromosomal mutations. Students need this basic information about genetics in order to
complete the lab. The lab asks students to carry out a gene/chromosomal mutation and then
transcribe and translate the nucleotide sequence in order to discover the type of beak the
offspring will possess.
The Bird Beak Lesson
Ms. Chen's bird beak experiment falls within a unit on genetics. In this simulation,
students gather data to see how beak mutations can influence natural selection. View Lesson Plan (pdf)
After the Lesson
After the lesson, students completed an individual performance task (pdf) that reinforced their knowledge of
concepts covered in the lesson and showed their understanding of those concepts.
The performance task asked students to pretend that they were doctoral
students doing research on a particular, randomly assigned species of wading bird. Their
research was intended to help them discover how this species of wading bird evolved from
an ancestral bird with a beak much like the tongue-depressor beaks used in the lab.
Students needed to incorporate real-life facts about their species of bird and use their
knowledge learned from the lab in order to write their explanation. Each student submitted
an abstract, similar to ones sent to scientific conferences, and presented their
information in an oral presentation. As an introduction to the performance task, Ms. Chen
showed pictures on an overhead different wading birds gave students a few facts about the
birds to pique their interest.
After completing the Performance Task, the class went on to discuss other
topics in genetics including karyotypes and genetic counselors, autosomal dominant and
recessive disorders, sex-linked disorders, and mitosis and meiosis. The genetics unit was
followed by plant structures, photosynthesis, cell respiration, animal structures, organ
systems, and comparative anatomy to end the year.