This is the new updated edition of the first book in the bestselling Uncovering Student Ideas in Science series. Like the first edition of volume 1, this book helps pinpoint what your students know (or think they know) so you can monitor their learning and adjust your teaching accordingly. Loaded with classroom-friendly features you can use immediately, the book includes 25 “probes”—brief, easily administered formative assessments designed to understand your students’ thinking about 60 core science concepts.

Access this probe as a Google form: English

Download this probe as an editable PDF: English

The purpose of this assessment probe is to elicit students’ ideas about temperature in the context of phases of matter. The probe is designed to find out if students recognize that the temperature of a substance does not change when two phases are present.

P-E-O

energy, phase change, phases of matter, temperature, transfer of energy

The best answer is C: The temperature of the ice water stayed the same. When an ice cube at –4°C is placed in a cup at room temperature (approximately 22°C), the surface of the solid cube absorbs thermal energy (sometimes called heat energy) from the surroundings. In the solid phase, the molecules are being held in a relatively fixed position, and the energy is used to overcome the attractive forces between the water molecules. When sufficient energy is absorbed, the solid ice begins to melt. For water, this phase change occurs at 0°C.

During a phase change, the temperature of the system remains constant as long as two phases are present. In this example, the temperature will remain constant at 0°C while ice and water are both present. When more ice is added, the temperature will continue to remain constant at 0°C. Because the phenomenon is taking place in a cup surrounded by air at a temperature of 22°C, once all the ice melts, the energy in the system will result in an increased motion of the liquid molecules, and the water temperature will gradually rise until it reaches 22°C.

Temperature, heat, and thermal energy are related terms that are often confused. Temperature is the measure of the average kinetic energy of the particles that make up objects or materials. Heat is the amount of thermal energy that is transferred between two objects or materials due to a temperature difference. In other words, heat is thermal energy in transition as opposed to stored thermal energy. Thermal energy is the amount of internal kinetic and potential energy in an object or material.

Elementary Students

In the elementary grades, students use simple instruments to gather data. They learn to use thermometers to measure temperature. At this stage, their experience with temperature is observational. This is a time when students learn about phases of matter and changes from one phase to another. They can observe how temperature remains the same as a substance such as ice melts, thereby building an experiential foundation for explaining the relationship among heat, temperature, and phase change later on in middle school.

Middle School Students

In the middle grades, students begin to explain what happens during a phase change in terms of temperature patterns and begin to use ideas about energy transfer. They typically graph the change from ice to boiling water and analyze their graphs to understand that the temperature remains the same as ice melts or water boils when two phases are present. Students in northern climates may draw on their everyday experience to connect the idea of the temperature of ice to weather-related phenomena, knowing that icy conditions happen when the temperature reaches 32°F (0°C). However, it may be counterintuitive to them that, after an extended period of time, the temperature of a sample of ice water (ice melting in water) sitting at room temperature will still be 0°C.

High School Students

Students at the high school level should be able to explain phase changes in terms of energy transfer. They should be able to extend their observations from ice to boiling water to predict what would happen if the steam continued to be heated. They should be encouraged to conceptually distinguish among heat, thermal energy, and temperature. However, memorizing the definition of these terms may not result in students being able to use them, such as in the example given in this probe.

This probe can be visually demonstrated to students by putting five ice cubes in a glass and letting the ice melt until there are small pieces of ice in the “ice water.” Then add five more ice cubes and ask students to predict what will happen to the temperature of the ice water after a few minutes. With older students, you may wish to change the probe to include quantitative responses. Make sure students understand that there are always some unmelted ice cubes present in the water. If the temperature were measured after all the ice had melted, the resulting temperature would be different. Note: Make sure students understand ice is not always 0°C. Ice can be colder than 0°C. 0°C is the melting point of ice.

• Driver and Russell (1982) carried out a study in which children were shown a beaker of ice with a thermometer reading of 0°C. The children were asked what would happen if more ice was added. Most of the 8-year-old children thought that the temperature would go up when more ice was added. Older children, up to age 14, thought that the temperature would decrease when more ice was added (Driver et al. 1994).
• Up to the age of 12, students are familiar with the term temperature and are able to use a thermometer to measure the temperature of objects or materials, but they have a fairly limited concept of the term. They rarely use temperature to describe the condition of an object (Erickson and Tiberghien 1985).
• Children do not recognize temperature as a physical parameter that can describe the condition of a material. They consider other criteria more pertinent for describing materials (Driver et al. 1994).
• Many 8- to 17-year-old students regard melting as a gradual process, unconnected with a particular temperature (Driver et al. 1994).
• Clough and Driver (1985) reported that students up to the age of 16 think of cold as “an entity which, like heat, has the properties of a material substance.” They do not necessarily think of hot and cold as part of the same continuum, but instead they think of cold as the opposite of heat (Driver et al. 1994).
• Students may use the intuitive rule “more A, more B” to reason what happens when you have more ice cubes (Stavy and Tirosh 2000). Using this rule, students may think that when there is more ice, there will be “more cold.”

Konicek-Moran, R. 2008. Everyday science mysteries: Stories for inquiry-based science teaching. Arlington, VA: NSTA Press.

Robertson, W. 2002. Energy: Stop faking it! Finally understanding science so you can teach it. Arlington, VA: NSTA Press.

National Science Teachers Association. 2006. NSTA Energy SciPak. Online at www.nsta. org/store/product_detail.aspx?id-id=10.2505/7/ SCB-GO.3.1

• This probe can be used as a P-E-O-E probe—Predict, Explain, Observe, Explain (again). Have students predict what would happen and explain the reasons for their predictions. Then have students test their ideas and observe what happens to the temperature. If their observations do not match their predictions, students are encouraged to come up with revised explanations.
• Use ABC—“activity before concept” (Eisenkraft 2006)—to provide an opportunity for students to experience the phenomenon and collect and analyze temperature data before presenting them with the concept of temperature during a phase change. Having students observe and construct their own explanations first before being presented with the formal scientific concepts is a more powerful way for students to learn.
• Use a real-life phenomenon to demonstrate that temperature remains constant during a phase change. Obtain an extremely large sample of crushed ice or, in northern climates during winter, fill a large bucket with snow from the school yard. Record the temperature of the snowy slush in the bucket throughout the day.
• Have students use phase-change graphs to analyze patterns and notice that when two phases are present (e.g., water in the liquid and solid form), the temperature remains the same.
• Be sure to explicitly develop the generalization that constant temperature during a phase change (melting, freezing, boiling, condensation) is true for all pure substances, not just water.
• Do not introduce the difference between heat and temperature in the context of this probe until students are ready to understand this difference. Up through late middle school, it may suffice to keep this idea at an observational level and hold off on explanations until students are ready.
• With older students, link the idea of energy transfer to phase change. Ask students to discuss why the temperature of the water remains constant and then increases as soon as all of the ice melts. What was happening to the energy while there was still ice in the system?