Effective Science
Article – 1st Draft
Erin E. Peters
The Periodic Table as
a Tool for Teaching Scientific Literacy
According to the National Science Education Standards, students in grades 5 to 8 are expected to use the properties of matter to distinguish and separate one substance from another. Showing students the underlying features of the organization of the Periodic Table of the Elements helps to accomplish this goal, but it is a daunting task. From a student perspective, understanding the multiple relationships shown in the periodic table can be overwhelming and abstract. One way to make the task of teaching the organization of the Periodic Table of the Elements meaningful to students is to demonstrate the role of categorizing and organization in the processes of science. Students can relate to the way everyday life is organized. Teachers can use this understanding to scaffold complex information from concrete to abstract knowledge.
The activity described in this article addresses both teaching standards and content standards from the National Science Education Standards. Teaching Standard A explains how teachers can plan inquiry-based science program for their students by selecting science content and adapt and design curricula to meet the interests, knowledge, understanding, abilities and experiences of students. This activity also addresses Teaching Standard B by allowing teachers to guide and facilitate learning. Understanding how and why elements are organized addresses the Content Standard for K-12, Unifying Concepts and Processes. This activity also addresses Content Standard A, Science as Inquiry and Content Standard B, Physical Science in that it requires students to ask questions to collectively discover the organization of the periodic table and the periodicity of properties of matter.
The Benchmarks for Science Literacy specify that student information should begin with concrete information and proceed to abstract information. In addition to satisfying that criterion, this activity demonstrates Benchmark 1A, the Scientific World view, by evoking student evaluation of the scientific merit of different organization systems. The activity shows students how imagination plays a part in making sense of collected evidence, as designated in Benchmark 1B, Scientific Inquiry. The parts of the activity that require students to find patterns in the properties of matter addresses Benchmark 4D, the Structure of Matter. The progression of ideas involved in this activity help to bring together ideas of science content and scientific processes in developing knowledge while transitioning from concrete to abstract knowledge.
Everyday Object Organization Activity
Students often enter the science classroom thinking that they do not understand science, but people naturally seek out patterns and explanations, a central function of science. Teachers can show students that by observing their everyday world, they already evoke scientific principles. This activity begins by asking students to use their prior knowledge to classify simple shapes. The shapes include paper cut-outs of different colored circles, rectangles and squares with borders and with numbers and letters written on them (see Figure 1). Students are given a graphic organizer to identify the overall system for organization, the breakdown of the categories, and the way the shapes fit into this system (see Figure 2). Students are put into groups of three or four and are given the graphic organizer that includes an example using color as a system. The students are then asked to be creative and find five different ways to categorize the same everyday objects and to write their information on the graphic organizer. The groups take turns reporting out on a unique classification system of their everyday objects to the rest of the class. Some of the organization systems given by students will sort the objects into several equally distributed groups and some organization systems will arrange the objects into one group that includes most of the objects and another group that includes the remaining single object. At this point, the teacher asks the students “Which organization system is more useful?” The pursuant discussion can be helpful in showing students why in some circumstances a scientist might want to single out an object in organizing (referring to the one big group and the one group with a single object) and why a scientist might want to organize the objects into more equally distributed groups.
Connections to the Nature of Science
Teaching factual science knowledge without teaching how the knowledge can be acquired rarely allows students to think above the recall level. When students are required to memorize facts of the Periodic Table they are not given the opportunity to learn how to learn. A more meaningful method of teaching the properties of matter is to have students understand why the Periodic Table is organized and to be able to use it as a tool to look up information about the elements. When students understand the principles under which scientists construct knowledge, they have the power to construct their own knowledge. Now that students have a basis for understanding why organization is useful, students will learn about an important organizational tool used in science. As called for in the Benchmarks for Scientific Literacy, students in this activity are guided from the concrete activity of organizing everyday objects to a more abstract one, categorizing elements on cards into different systems.
Element Organization Activity
Groups of students are given the same set of cards that have information such as symbol, name, atomic number, number of valence electrons, atomic radius, and general physical properties for each element from atomic number 3 to atomic number 20 (See Figure 3). Students are asked to decide on one organization system for their deck of cards and justify why they chose their categories. When all groups have reported out their choice for organization of the cards to the entire class, the teacher asks students which types of organization are based in nature (scientific) and which systems are based on human constructs (non-scientific, but still valid). Some questions that can get student discussions initiated are:
- What might be some criteria that would make one grouping system more useful than another?
- Are some grouping systems that you named more useful than others?
- If the grouping systems are equally valued for their usefulness, how would a scientist choose which system to follow?
- How might scientists agree on which system to follow?
Seeking patterns
After the student discussions, the teacher tells the class that there is one known organization system that allows for many different properties to be grouped together and that the following part of the activity will help them discover that system. The teacher asks the students to line ups the cards in order of atomic number. When students have the cards lined up, they look for other patterns that occur due to arrangement of the elements by atomic number. Students recognize several patterns: valence number is increasing by one until it gets to eight, then begins again, atomic radius decreases, then increases and begins to decrease again, or properties of the elements also form a repeating pattern.
Students begin to realize that by ordering the elements by atomic number, that other types of organization systems develop naturally, reinforcing the idea that patterns occur in nature and it is the role of scientists to find and describe these patterns. At this point in the lesson, it is important that the teacher connects the idea of repeating patterns to the vocabulary “periodic”. When students are prompted to give examples of things in their lives that form repeating patterns, they often respond with examples such as meal times, the days of the week, or the months of the year.
If it isn’t brought up by a student, the teacher can ask for an alternate name for “classes”, which is “periods”. Students attend first period, then second period, then third period and so on. Each day the pattern repeats again, just as it does in the periodic table of the elements. Because information from students’ everyday lives is connected to abstract scientific information, the name “Periodic Table of the Elements” has much more meaning. Students compare their card organization with the structure of the periodic table and observe that the periodic table is organized in the same way. The Periodic Table of the Elements is structured to give a great deal of information if the observer understands what to look for. Since students construct knowledge about the underlying patterns that are formed when the elements are put into order by increasing atomic number, they have access to the Periodic Table of the Elements as a tool to look up information about elemental features.
Mendeleev’s Process
There were several versions of the table of the elements before Dmitri Mendeleev proposed his adaptation. Being an enthusiastic card player, Mendeleev wrote the 63 known elements on separate cards and repeatedly laid them out to discover patterns. He realized that when he ordered the cards by atomic mass, as atomic number was not known in 1869, that chemical and physical properties of the elements formed a repeating pattern. From his version of the Periodic Table, Mendeleev predicted the existence of several undiscovered elements which were found during his lifetime. The scientific community continues to use Mendeleev’s basic idea for the periodic table of the elements with the exception of ordering the elements by atomic number rather than atomic mass, because it has been the most useful organization system to date.
Process and Content Connected
When students are given only factual knowledge, two major conflicts occur. The first is that students do not feel responsible for constructing knowledge because they are being fed facts by the teacher. Students feel that the information that constitutes knowledge is fixed and only available to authorities such as teachers, so they passively wait for their education. Another conflict occurs when students are given scientific facts as if they were in the final form, and then told that ideas in science change over time. When students are given the opportunity to find out how scientific knowledge is gained as well and the knowledge itself, then students are empowered to construct knowledge actively. As a result of participating in this series of activities, students are exposed to both the factual knowledge that is provided by the Periodic Table of the Elements and to the scientific processes and habits of mind that are required to produce scientific knowledge.
References
American Association for the Advancement
of Science. (1993). Benchmarks for science literacy.
Brooks, J. G. & Brooks, M. G. (1999).
The case for
constructivist classrooms.
Duschl, R. A. (1990). Restructuring science
education: The importance of theories and their development.
National Science Foundation. (1996). National science
education standards.
Figure 1
Shapes for Everyday
Object Organization Activity
|
Shape |
Color |
Border/No Border |
Size |
Letter/Number |
|
Rectangle |
Blue |
No border |
Small |
None |
|
Rectangle |
Red |
Border |
Large |
X1 |
|
Rectangle |
Yellow |
Border |
Large |
Y1 |
|
Circle |
Blue |
No border |
Small |
Z1 |
|
Circle |
Yellow |
Border |
Large |
None |
|
Circle |
Red |
Border |
Large |
X2 |
|
Square |
Blue |
Border |
Small |
Y2 |
|
Square |
Yellow |
Border |
Small |
Z2 |
Figure 2
Graphic Organizer for
Shape Categorization
System: Color
|
Categories |
Members |
||||
|
Red |
|
||||
|
Blue |
|
||||
|
Yellow |
Z2 Y1 |
Figure 3
Example of Element
Cards
Figure 4
Possible Element Card
Arrangements
|
Category |
Systems |
Type of categorization |
|
Alphabetical by Name |
A-Z by name of element |
Non-scientific |
|
Alphabetical by Symbol |
A-Z by first letter of symbol |
Non-scientific |
|
Number of letters in symbol |
One letter or two letters |
Non-scientific |
|
Atomic number |
2-20 |
Scientific |
|
|
Group with 1 valence, group with 2 valence, group with 3 valence and so on |
Scientific |
|
Atomic radius |
Ascending or descending atomic radius |
Scientific |
|
Properties |
Groups with similar properties |
scientific |
Figure 5
Possible Extensions
of Activity
Write a summary
paragraph
Reflecting on the information you learned today, write a paragraph using the following words to explain how the Periodic Table of the Elements is organized.
- Organization
- Scientific
- Elements
- Periodic
- Valence electrons
- Atomic number
- Properties
- Atomic Radius
Write an editorial
supporting Mendeleev’s prediction of missing elements
Before the predicted elements were found, Mendeleev’s hypothesis that elements needed to follow a pattern was controversial. Many scientists did not think that organizing elements by property was enough evidence to predict unknown elements. Suppose you lived during this time period, write an editorial article to the local newspaper supporting Mendeleev’s predictions.
Make a periodic table
of food
Given 12 different dried foods such as beans, rice and pasta, create a periodic table of food. Be sure to organize your food groups in as many ways as possible. You can even find the “atomic mass” of each food by using a scale.
Investigate the
properties that are common to each group of elements
The Periodic Table of the Elements organizes elements in a column called “groups” or “families”. Use library materials to research the common features of each group on the periodic table. How could you include this information in today’s activity?
Figure 6
National Science
Education Standards
|
Standard |
Description of
Activity |
|
Teaching Standard A: Inquiry-based program |
Organizing everyday objects helps to connect scientific organization to student prior knowledge |
|
Teaching Standard B: Teacher facilitated science activity |
Students create simplistic systems of organization and through activities begin to see the sophistication of the organization system of the Periodic Table of the Elements |
|
Content Standard K-12: Unifying Concepts and Processes |
Understanding of the criteria for using scientific principles for organizing the Periodic Table of the Elements |
|
Content Standard A: Science as Inquiry |
Using logic without having to follow a step-by-step method |
|
Content Standard B: Physical Science |
Properties of Matter |
Benchmarks for Science Literacy
|
Benchmark |
Description of
Activity |
|
1A: The Scientific World |
Student evaluation of scientific merit of organization systems |
|
1B: Scientific Inquiry |
Imagination plays a part in making sense of collected evidence |
|
4D: The Structure of Matter |
Finding patterns in the properties of matter |