by Vanashri Nargund
and Meredith A. Park Rogers
T
he periodic table is one of the first scientific models introduced at the middle school
level. The National Science Education Standards describe scientific models as “tentative schemes or structures that correspond to real
objects, events, or classes of events, and that have
explanatory power” (NRC 1996, p. 117). Specifically,
the periodic table explains how a variety of natural
and synthetic elements can be organized systematically to determine patterns and relationships from elements’ properties. Learning how the periodic table
has developed over time can provide an important
foundation for students’ future science learning, as
they begin to explore the explanatory power of other
models in science. In this activity, students are given
the opportunity to investigate the generation of the
modern periodic table, through a process of creating
their own plausible periodic tables.
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Connections to scientific literacy
In addition to learning science content, reform efforts in science education have placed an emphasis on
students learning about the nature of science (NOS)
and scientific inquiry with the goal of students becoming more scientifically literate (e.g., AAAS 1989; NRC
1996). It is repeatedly stated in the research literature
that for students to form a conceptual understanding
of NOS and inquiry, instruction must be explicit and
reflective (Akerson, Abd-El-Khalick, and Lederman
2000), while also contextualized within science content
(Clough 2006; Ryder, Leach, and Driver 1999). Teachers can help students understand aspects of NOS and
the skills of scientific inquiry through explicit discussions (one on one or whole class) during each phase
of their instruction. Taking the time to build these connections into the lesson at the moment students are experiencing inquiry and the nature of science will help
That is Not Where That Element goes…
to facilitate better conceptual understanding. Figure 1
provides suggestions for which aspects of NOS and inquiry to discuss with regard to this lesson.
Exploring the periodic table: From past
to present
Working with middle school students has taught us
that many students think there is only one form of
the periodic table and that it has never changed over
time. However, through understanding the tentativeness of science, students can learn that the modern
periodic table has developed through multiple revisions and representations the more scientists have
learned about elements and their properties. Most
scientists credit the current version of the periodic
table to Dmitri Mendeleev’s original work from the
mid-1800s. Mendeleev, known as the father of the
periodic table, was the first to notice patterns in the
properties of elements. He took 63 known elements
and arranged them by their atomic mass; he began to
notice patterns, which enabled him to make predictions about other possible elements and their properties. While the modern periodic table is arranged
according to atomic number and not mass, it was
Mendeleev’s insight into the potential of organizing
elements in periodic groups that has guided scientists
over the years to continue rethinking the best way to
arrange elements as new ones are discovered. The
purpose of this activity is to introduce to students the
notion of how scientific models (such as the periodic
table) continue to evolve and the role of scientific inquiry in this process (see Figures 2a and 2b).
Engage
(Note: The activity in this phase has been adapted
from NASA Jet Propulsion Laboratory materials [see
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References]). Employing Bybee’s (2000) 5E instructional model, the purpose of this phase of instruction is to determine students’ prior experience with
the content and grab their attention about the topic
of study. Students begin this phase working in small
groups to solve a 12- to 20-piece puzzle of a picture of
a scientist who has contributed to the development
of periodic table. Each group is assigned a unique
contributing-scientist puzzle. To prepare for the activity, the teacher should separate each puzzle into two
unequal piles of pieces and place the larger pile into
an envelope marked A and the smaller pile into an
envelope marked B. Also, remember that each group
FIGURE 1
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gets a unique scientist, so number the puzzle pieces
on the back as 1A and 1B, 2A and 2B, and so on, in
case pieces get misplaced. Using envelope A, students put the puzzle together using clues such as the
background color of each piece, outline of the shape,
or any relevant information from the pictures, and record their strategies in their science journals. After
a little time has passed, students will begin to realize that there are pieces missing from the puzzle. Ask
students “How do you know that pieces are missing?
What is your prediction about the characteristics of
the missing pieces?” As mentioned earlier, envelope A
has more pieces, which will help students to solve the
Periodic table activity at a glance
Inquiry
phase
Learning task
Aspects of NOS
(McComas 1998)
Inquiry skills
(Harlen 2001)
Engage
•Students will piece together a puzzle, recording
their strategies.
observation versus
inferences
observation, prediction,
inferring
Explore 1
•Student groups will develop their own classification structure from element cards and develop
pictorial presentation of their ideas to share with
the class.
empirically based,
creativity and
imagination
observation,
questioning, planning,
interpreting information
Explain 1
•The teacher facilitates a whole class discussion
where students examine each other’s classification
structures looking for similarities and differences.
•Discuss the meaning of the different terminologies on the cards and have an explicit discussion
of the aspects of NOS represented in the activity
so far (see next column).
subjectivity, creativity
and imagination,
tentativeness of ideas
in science
interpreting information,
hypothesizing
communicating
Explore 2
•Students will read and discuss in their groups
about the history of periodic table and about
Mendeleev’s work.
creativity and
imagination,
tentativeness
observation, interpreting information, prediction, hypothesizing
Explain 2
•Discuss with students input how empirical data are
used to design models, thus the arrangement may
change with new evidence. Also, describe Mendeleev’s arrangement of the elements and his ability
to “interpolate” from this arrangement to discover
new elements. Relate Mendeleev’s process and
model to students’ jigsaw puzzle experience and
what they interpolated from the puzzle.
tentativeness, creativity,
empirically based,
subjectivity
interpreting,
communicating
Elaborate
•Students will compare different periodic tables
noting similarities and differences, groupings,
and periods. Discuss reasons for today’s accepted periodic table as the standard.
creativity, empirically
based, cultural and
social embedded
observations,
interpreting information,
communicating
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That is Not Where That Element goes…
puzzle and formulate predictions of missing pieces.
Have students make specific observations about the
various puzzle pieces they have, including any inferences they can make about the missing pieces. Next,
give them envelope B and let them complete the puzzle. When you give students envelope B with the rest
of the pieces, students can complete the puzzle and
confirm their predictions. Ask them to compare these
new pieces to the inferences they have made about
the missing pieces. What observations helped them
most in making accurate inferences? What pieces are
they still confused about and why? Is there an aspect
of the original puzzle that is still missing? If so, why
do they think this is and what might this be? To raise
multicultural awareness about the practice of science,
teachers can discuss how scientists from different
countries have built upon each other’s work over the
years to contribute to the generation of the modern
periodic table. This phase can take around 30 minutes, including puzzle solving and discussion.
Explore 1
This part of the 5E instructional model is geared toward developing students’ conceptual understanding
by providing them first with an opportunity to explore
different methods for classifying the elements before
being asked to “explain” and justify their strategies
(Gagnon and Abell 2008). A teacher will need to make
45 different element cards for each group (see Figure
3). Once one set of 45 is made, the set can be copied
to make enough for all groups in the class. Elements
from both lower and higher atomic numbers should
be included, as well as elements from metal, nonmetal, and metalloid groups. Selecting from these various
categories will ensure that students are working with
a variety of elements.
Begin by giving each group 30 of the 45 element
cards. Ask students to group these cards as they
wish, but be sure that they record their different sorting strategies, noting those that work well and those
that do not (see Figure 4). Next, have them create a
pictorial representation of the grouping that they think
works best and give it a name, which they will then
share with the class. Facilitate this discussion with
questions such as “Do you think you have sufficient
information for justifying your groupings? What are
some possible sources of error in your organization?”
Finally, provide each group with a new set of element
cards (approximately 15) and have them try to fit
these new cards into their chosen grouping. If a card
FIGURE 2a
Learning objectives for the
periodic table activity
Students should be able to do the following:
Demonstrate how they used different process skills
related to inquiry science in the creation of their own
periodic table.
Describe how the creation of the periodic table is an
ongoing human endeavor, and identify other tenets of
NOS they employed (e.g., empirical bases of science,
differences between observation and inference, subjectivity, etc.).
Communicate relationships and patterns between
different properties of elements when configuring their
own periodic table and comparing others.
FIGURE 2b
Standards addressed with the
periodic table activity
National Science Education Standards (NRC,1996)
Teaching standards
Guide and facilitate student learning by:
•Orchestrating discourse among students about
scientific ideas.
•Challenging students to accept and share
responsibility for their own learning.
•Encouraging and modeling the skills of scientific
inquiry, as well as the curiosity, openness to new ideas
and data, and skepticism that characterize science.
Content standards
•Inquiry
•Abilities necessary to do scientific inquiry
•Understanding about scientific inquiry
•Physical science
•Properties, structure, and changes of properties in
matter
•History and nature of science
•Science is a human endeavor
•Nature of science
•History of science
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That is Not Where That Element goes…
does not fit their pattern, ask students to note why it
does not, and to make suggestions for reorganizing
their periodic table so that all the cards fit. Possible
questions to scaffold their modifications might be the
following: How did you fit these new elements into their
groups? What revisions, if any, did you have to make
to your card groups to fit these new cards? Why were
these modifications necessary? Prior to this activity,
any versions of the periodic table should be removed
from the classroom. Also, students should be encouraged to use their creativity and imagination while doing
this activity and not rely on other resources. Teachers
can encourage students to develop creative, but useful,
arrangements by informing students that there is not
one correct or right answer.
Explain 1
The Explain phase provides the teacher and students
an opportunity to build explanations together on the
basis of the observations students made during the
Explore phase. This is the stage where new scientific
vocabulary, such as atomic number, atomic mass number, valance electrons, metals/nonmetals, metalloids,
and so on, can be introduced based on students’ explorations. To begin this phase, bring everyone together
and have students share their organizational structure
visually with the class. Encourage them to discuss
similarities and differences among the groups’ different structures. Guide the discussion with questions
such as the following: What property on the card did
you primarily use for grouping your elements? Why?
Do you know what this property refers to? (Be sure
to allow time for students to explain what these properties mean.) Your goal with this conversation is to
help students think and explain their reasoning for
their organizational structure and to guide students
to the realization that there is not one right way to organize the elements. Science is, by nature, subjective,
creative, and tentative. As we get new evidence, new
models are proposed or older models revised.
Explore 2 and Explain 2
Organizing a science learning experience where students are asked to work through multiple Explore and
Explain phases can provide the necessary scaffolds
for developing a deeper level of understanding. It also
provides an opportunity for the teacher to formatively
assess students’ understanding about the concepts so
that they can modify their instruction to meet students’
individual learning needs. Therefore, students will go
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through one more Explore and Explain phase in this
activity before they are asked to apply their knowledge
in the Elaborate phase. These second Explore and Explain phases will provide the teacher with another opportunity to find out what students know, and to assess
if they are ready to move on to the application of their
knowledge in the Elaborate phase.
Students will learn about the history of the periodic
table through their study of Mendeleev’s work. The
teacher needs to decide the best method for having
students read through historical text on the development of the periodic table. For example, we recommend providing a few journaling questions to guide
students through their reading (e.g., In what ways do
you think previous models of the periodic table helped
to develop the current model of the periodic table?)
Next, hold a class discussion of critical points from
the readings explicitly connecting aspects of NOS and
scientific inquiry to the evolution of the periodic table.
Possible questions for this discussion may include the
following: Why do different scientists propose different
FIGURE 3
An example and template of an
individual element card
That is Not Where That Element goes…
models for the periodic table? How can these models
be used for understanding future undiscovered elements? Compare the organization of your elements
from the previous activity with these models. What
are some similarities and differences? Are there some
element properties the other models used that you
didn’t consider for your model? How do you think these
properties helped scientists to classify the elements
differently? You will also want to encourage students
to discuss the role of empirical data in designing or
revising models in science. For example, how did
Mendeleev use data to arrange the elements and then
use this arrangement to help predict undiscovered elements? Draw students’ attention to the puzzle activity
they performed at the beginning of this investigation
and compare how Mendeleev’s approach was similar
or different from their problem-solving process. The
concept of interpolating information from limited data
sources could also be discussed at this time, as could
the different process skills students used and how they
are employed by real scientists (see Figure 1).
FIGURE 4
Elaborate
In this phase of the activity, students are asked to apply
their knowledge. Begin by giving students a variety of
periodic tables (see Figure 5), including the modern
periodic table. Let students observe these various
formats of the periodic table. Ask them to compare
these tables (looking at various properties of the elements) with those they developed in Explore 1 and
with Mendeleev’s version. The discussion can start
with what students found interesting and surprising
about these other forms of the periodic table, leading
into a discussion about how Mendeleev’s model is different from the modern periodic table (e.g., atomic
weight versus atomic number). Give students time to
formulate their own questions about element periodicity after comparing these different periodic tables.
Evaluate
To know when to proceed with instruction or when to
pause and provide additional support is a critical element of reform-minded teaching and requires that the
Organization of element cards
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FIGURE 5
Different types of periodic tables
FIGURE 6
Rubric for the summative assessment
While comparing the periodic tables,
students did the following:
•Used observation skill
•Used and explained meaning of
different properties of elements
•Built explanations based on the
empirical evidence
•Displayed and identified different
process skills
•Identified different aspects of NOS in
the journey of the periodic table from
Mendeleev’s model to the modern
periodic table
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4 = Exemplary
3 = Proficient
2 = Adequate
1 = Unsatisfactory
That is Not Where That Element goes…
teacher employ a variety of formative assessment strategies (Abell and Volkmann 2006). For example, within
this activity we had students write down their strategies for solving the puzzle during the Engage phase,
which we could then examine as we walked around the
room to get a sense of the kinds of ideas they were trying out. A similar recording activity was incorporated
into Explore 1, which also encouraged students to selfassess as they determined the effectiveness of their
various organizational strategies. Summative assessment may occur during the Elaboration phase when
students are asked to describe their understanding of
model building by applying their Explore and Explain
phase experiences to the process of comparing various
models of the Periodic Table. In the past we have used
an exit slip during the elaboration phase of this lesson;
a strategy in which the students individually respond
to a set of teacher developed questions targeting the
lesson’s learning objectives. Figure 6 provides suggestions on what to assess in these slips.
Suggestions for modifying the activity
Throughout this activity, students explore different
perspectives of the periodic table and think about how
scientists’ efforts, imagination, and creativity are used
to generate organizational structures that can be applied as a tool for understanding broader chemistry
concepts. While this lesson was originally designed for
upper middle school/early high school grades, it has
the flexibility to be modified for students needing additional support and those needing more of a challenge.
To gear down the activity, give students real-life substances made up of different elements and ask them to
identify and classify the substances according to different properties of the substance (e.g., small utensils made
up of steel, a lock and key combination made up of brass,
cutlery made of silver, etc.). It is best to use common,
everyday, and nonhazardous alloy materials for this
extension activity. To gear up the activity, have students
write a paragraph on how the periodic table may look
50 years from now, using their knowledge about NOS
and inquiry to support their explanations. n
Resources
Marie Curie and the science of radioactivity: History of the
periodic table—www.aip.org/history/curie/periodic.htm
The Chemogenesis webbook: Periodic table formulation—
www.meta-synthesis.com/webbook/35_pt/pt.html
The element database: periodic table—www.elements
database.com/Images/periodic_table1.gif
The New York Times spiral periodic table— www.nytimes.
com/imagepages/2006/10/23/science/20061024_
ILLO_GRAPHIC.html
The periodic table of videos—www.periodicvideos.com/#
Sterling, D. 1996. Discovering Mendeleev’s model. Science Scope 20 (2): 26–30
References
Abell, S.K., and M.J. Volkmann. 2006. Seamless assessment in science: A guide for elementary and middle
school teachers. Portsmouth, NH: Heinemann.
Akerson, V.L., F. Abd-El-Khalick, and N.G. Lederman.
2000. Influence of a reflective explicit activity-based
approach on elementary teachers’ conceptions of
nature of science. Journal of Research in Science
Teaching 37 (4): 295–317.
American Association for the Advancement of Science
(AAAS). 1989. Project 2061: Science for all Americans. Washington, DC: AAAS.
Bybee, R.W. 2000. Teaching science as inquiry. In Inquiring into inquiry learning and teaching in science, eds.
J. Minstrell and E.H. van Zee, 14–19. Washington, DC:
American Association for the Advancement of Science.
Clough, M.P. 2006. Learners’ responses to the demands
of conceptual change. Considerations for effective
nature of science instruction. Science Education 15
(5): 463–94.
Gagnon, M., and S.K. Abell. 2008. Perspectives: Explaining science. Science and Children 46 (5): 60–61.
Harlen, W., ed. 2001. Primary science: Taking the plunge:
How to teach primary science more effectively for ages
5 to 12. 2nd ed. Portsmouth, NH: Heinemann.
McComas, W., ed. 1998. The nature of science in science education: Rationales and strategies. Netherlands: Kluwer Academic.
NASA Jet Propulsion Laboratory. Cosmic chemistry: An
elemental question. http://genesismission.jpl.nasa.
gov/educate/scimodule/indexCC-EQ.html
National Research Council (NRC). 1996. National science education standards. Washington, DC: National
Academies Press.
Ryder, J., J. Leach, and R. Driver. 1999. Undergraduate
science students’ images of science. Journal of Research in Science Teaching 36 (2): 201–20.
Vanashri Nargund ([email protected]) is an
associate instructor and a doctoral student of science
education at Indiana University in Bloomington,
Indiana. Meredith A. Park Rogers (mparkrog@
indiana.edu), a former elementary school teacher, is
currently an assistant professor of science education
at Indiana University in Bloomington, Indiana.
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