The first learning target of the
school year entailed familiarization with the parts and operation of a
microscope, observation
of specimens—ranging from microorganisms (e.g., tardigrades, rotifers,
nematodes) to plant (e.g., elodea, onion) and animal cells (e.g., students’ own
swabbed cheek cells, amoeba), and preparation of wet mounts. During my focused observation of
my mentor teacher’s periods 3, 4, and 6 biology classes, I witnessed student
response to direct instruction and the corresponding forms of questioning [2.1].
Direct instruction is explicit teaching of concepts and procedures using
lectures or demonstrations of the learning material to students.
For the first 10-15 minutes of a
period of Biology, my mentor teacher lectured on the parts of a compound microscope using
a camera-projector and provided background information on the microorganisms
used for compound microscope practice with a PowerPoint presentation. Afterward, I interacted with each individual
student in order to assess for understanding of the microscope parts,
calculation of magnification, and how to use the microscope. Once I saw
that they understood what they needed to about the microscope, I signed
their handout so that they could proceed to practice microscopy with the moss
petri dishes they prepared [6.4].
In
the days following, I had an opportunity to use direct instruction in conducting
a demonstration and lecture for the subsequent class periods after having
observed my mentor teacher demonstrate for 10-15 minutes using a document
camera-projector on how to prepare microscope slides of plant cells—elodea and
onion—and animal cells—the students’ own cheek cells and purchased whole mount
microscope slides of amoebas—for use in practicing microscope operation and
explain using a PowerPoint presentation acceptable and unacceptable examples of
documentation of microscope findings. For this specific lesson, students were
expected to continue familiarizing themselves with the microscope and learn how
to adjust the microscope in order to get an introductory look at the different,
observable cell parts that was then introduced the following day through a
lecture spanning for most of each class period. Specifically, this lab required
students to properly focus the compound microscope so that they can then
illustrate their observations on a pre-formatted handout provided by the
teacher. Students worked in with their tablemates (each table group contain 3-4
students). Findings were reported with illustration and description.
Closed-ended questioning was used throughout the demonstration
and lecture, specifically because most of the students had no background
knowledge of microscopy use or the specimens utilized for practicing microscope
usage. At the very beginning of class, my mentor teacher stated that the day’s
learning objective:
· In table groups, students need
prepare two microscope slides: one of an elodea leaf and one of a group member’s
swabbed cheek cell(s).
· Students are instructed to replicate
the procedure my mentor teacher demonstrated on preparation of microscope
slides with the target specimens (e.g., elodea, human cheek) in order to
further practice their ability to properly focus the compound microscope for
study of specimens and familiarize themselves with the different parts of the
plant cell (i.e., elodea) and animal cell (i.e., human cheek) as an
introduction to a comparison of plant and animal cells.
Immediately
following the demonstration, my mentor teacher shared poor and excellent
examples of student observations using the compound microscope and
corresponding documentation with illustrations and descriptions. For most the
PowerPoint presentation, my mentor teacher told the students the reasoning for
acceptable and unacceptable examples of documentation of observations with the
compound microscope.
During my turn to lecture and demonstrate procedures to the
students, I prompted students to think about the content by asking them, “if
someone could tell me why this is the case?” More often than not, students
raised their hands to volunteer answers. Students who raised their hands
to volunteer answers were of no particular ability: one student is categorized
as 504—noted as having an undefined learning disability—and another has no
special notation on their student file. I did not have to resort to
cold-calling on students to volunteer answers. A willingness to volunteer
answers to prompts might indicate that the learning environment is one of
respect and students feel safe to participate [5.1].
