Directions: After using the Science News article “The periodic table turns 150” to review why the periodic table is considered a “model” in science, use the questions below to engage your class in a discussion about the principles and purposes of scientific models in all areas of science and engineering.

Suggestion for structuring discussion: Divide your class in half. Create either two lines or two concentric circles of students so that each student is facing a partner. Ask a question and allow students to answer the question with their partner. After the question is answered, direct students to rotate to a new partner. Once all questions are answered in pairs, ask students to return to their seats, and pick a few questions to review with the entire class.

Discussion background for the teacher: Dmitrii Mendeleev conceived the idea of the table by creating an organized system of known elements and used the organized system to predict the existence and properties of unknown elements. Mendeleev helped create one of the most notable and useful scientific models known today, the periodic table. When trying to explain some aspect of nature, developing systems and models is a common practice in all areas of science and engineering.

Discussion questions for students:

1. What is a system?

A system is an organized group of related components.

2. What is a model? Give an example of a model.

A model is generally thought of as an ideal representation of a concept, process or object, which is used to predict or explain an outcome. Meteorologists use models to predict the weather, and architects use models to plan and design urban structures.

3. What is a scientific model, and what is its purpose?

Scientific models are tools that organize a system so that it is well understood. The model can be used to predict and explain behaviors and outcomes of the system.

4. Are scientific models correct representations of natural phenomena? Explain.

Some models attempt to represent natural phenomena but are human inventions that are generally oversimplified and flawed. Models are often guided by a set of assumptions that minimize the numerous variables affecting the predicted behavior of the system.

5. How do models typically change over time?

As new technology guides experiments that test the validity of a scientific model, models are often “patched” or corrected over time. If a model is fixed a number of times, it can become more complicated. Sometimes a new model can take the place of a predecessor.

6. Apart from the periodic table, what is another scientific model that is discussed in the article? How is its development similar to that of the periodic table’s?

The model of the atom is discussed toward the end of the article. Similar to the periodic table, the atomic model changed over time to accommodate experimental findings, such as Ernest Rutherford’s discovery of the atomic nucleus, from the results of his gold foil experiment. Many scientists contributed to the creation and modification of both models over time.

7. Think about the different fields of science — chemistry, biology, environmental science, physics, genetics, and so on. What are some examples of other scientific models from these fields?

The plate tectonic model of the Earth can help predict geologic activity. Climate models are used to help predict weather patterns and how climates change. The biological evolutionary model explains how earlier species give rise to current species via natural selection. The wave-particle duality model of light (or the combination of the wave model and the particle model) can help predict the behavior of light. The ideal gas model allows a simplistic prediction of interactions in gaseous system based on a set of given conditions. Three-dimensional computerized models of proteins and protein receptors can help inform and assist drug design. Models of animal and plant populations can help predict ecological interactions and population dynamics.