WhatBelongsin Your 15-Bean Soup? - NSTA Learning Center

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T E A C H I N G S T R A T E G I E S
each group. Then they are instructed to devise and
test a dichotomous key. This is a standard approach
used in many classrooms. The value of this activity
is indicated by numerous and innovative techniques
for implementing hands-on classification activities
using jelly beans, cars, or potato chips, for example.
Standard classification activities lead to development
of skills such as observing, interpreting variability,
and sorting related objects into groups. However,
biological classification systems utilize two
separate information-processing stages—sorting and
ranking. Construction of keys that allow others to
discriminate the same groups is just one product of
biological taxonomy. The primary product is a classification
scheme that mirrors the biologist’s understanding
of the historical evolutionary relationships
among similar species. Standard classroom
activities that only involve sorting can lead to misconceptions
about biological classification of organisms
because they leap from sorting to naming,
omitting the ranking process.
A second misconception is that keys are derived
from a classification. Keys are logical devices constructed
by experts that allow others to easily identify
unknown objects. A key allows a user to match
an unknown object with its name, which is not a
function of the classification system. A classification
system reflects the degree of relatedness among the
included species.
One approach to teaching concepts and addressing
misconceptions is the Learning Cycle. The Learning
Cycle was introduced in the 1960s as an inquirybased
teaching technique consisting of three stages:
Exploration, Concept Introduction, and Application
(Beisenherz and Dantonio 1996). The Exploration
phase consists of unstructured, hands-on activities
leading to observations and data collection. The
teacher can identify misconceptions by listening carefully
as students explain their observations. In the
Concept Introduction stage, the scientific concept
that explains what students observed in the first stage
is introduced, including appropriate vocabulary. The
teacher may use textbooks or other materials to
present the concept. In the Application phase, students
pursue more focused
activities that reinforce or
extend basic concepts. The
Learning Cycle can be used
Explore classification at
www.scilinks.org.
Enter code SS110401.
to address some of the misconceptions
about biological
classification.
FIGURE 1
Secret sort, Exploration phase
Objective
Students will collect and sort materials gathered from their
environment.
Materials (per group of four students)
one shopping bag
two or three 100-cm lengths of yarn
three index cards
newspaper to cover table
small objects collected by students
Procedure
1. Divide students into groups of four and give each group a
shopping bag.
2. Explain to students that you want each group to collect as
many small objects lying on the ground as possible during a
15-minute walk in an assigned schoolyard area. The entire
collection should fit inside the shopping bag.
Safety note: Students should be cautioned to avoid
collecting live animals, animal droppings, broken glass,
or sharp objects. If poison ivy, poison oak, or poison
sumac are present in the collection area, students should be
shown which plants to avoid.
3. In the classroom, students spread newspapers over the
desktops, then sort their materials into separate piles, or
categories. They use the yarn to form loops to enclose groups
of items. Loops may be overlapped or objects placed outside
the loops. There is no right or wrong way to sort.
4. Secret sort: Ask each group to think of a word to describe
each category, write it down on an index card, and place the
card face down near the pile (for example: natural vs.
manmade, or living vs. nonliving).
5. Groups then take 10 minutes to move around the room and
guess how other groups sorted their objects.
6. To wrap up the Exploration phase, the teacher organizes a
table on the board with a column for each group. Hypotheses
made about criteria for grouping, as students move around
the room, are listed in rows for each student group. In the last
row, each group’s explanation of their secret sort is given.
7. Closure: The teacher explains that the basis of sorting,
such as the secret sort, is grouping two or more items that
have something in common. This process is fundamental
to classification.
8. Alternative collection options: Students may bring objects from
home, or the class may use materials collected by the teacher.
24 science scope Nov/Dec 2004