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.

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The purpose of this assessment probe is to elicit students’ ideas about condensation. The probe is designed to determine whether students recognize that condensation comes from the water vapor in the air.

Familiar Phenomenon

condensation, evaporation, water cycle, water vapor

The best response is A: A gas in the air. The phenomenon described in the probe is the condensation that occurs on the outside of a cold object when the object comes in contact with warmer air that contains water vapor. Water vapor is an invisible gas found in the air around us. When the air molecules containing water vapor come in contact with a cold object, the water vapor in the air changes to liquid water on the cold object. It is this water that comes from a gas in the air called water vapor, that forms the puddle. Water condenses on the outside of the container and drips down to form a puddle. At a molecular level, when the molecules of water vapor come in contact with a cold object like the container of ice cubes, they slow down and move closer together. As the molecules move closer together, the attraction between molecules increases and they cluster together to form liquid water.

This phenomenon appears in several everyday examples, such as the condensation that occurs on your bathroom mirror after a hot shower; the wet dew on the morning and evening grass; the wet glass of lemonade poured on a hot, humid day; the wetness on the outside of a window of a cool, air-conditioned house; and the wetness on the inside of a car window during the cold winter when water vapor from exhaled breath condenses on the cold windows.

Elementary Students

In the early elementary school grades, the emphasis is on observing and describing observable phenomena, such as the condensation that occurs on the outside of a cold object. Students should have multiple opportunities in different contexts throughout the elementary grades to observe changes in state, such as solid to liquid, liquid to solid, liquid to gas, and gas to liquid. As students progress to the upper elementary school grades, they begin to develop explanations for these phenomena. An explanation of condensation is combined with an explanation of evaporation—that water leaves open containers and bodies of water and exists in the air around us in a gas form we cannot see called water vapor. The molecular explanation of evaporation and condensation can wait until middle school. More important than developing the vocabulary words condensation and evaporation is first developing a conceptual understanding of the processes linked to observable phenomena. Once students understand what is happening to the water, the vocabulary can be introduced and used with meaning.

Middle School Students

The water cycle is of profound importance for middle school students’ understanding of Earth systems. However, before the idea of the cyclic nature of water is developed, teachers need to be sure students understand what happens to water during a change in state. By the end of eighth grade, students should be able to use their understanding of the motion and position of molecules to explain changes in state and properties of solids, liquids, and gases. Many middle school students use the terms evaporation and condensation, which are words introduced at the elementary school level, without completely understanding where the water goes after it evaporates and why it condenses. Furthermore, students at this age still have difficulty accepting that air is matter and that there is water in the air in a form we cannot see. In order to explain everyday phenomena such as the one described in this probe, several of these ideas need to be integrated at the middle school level.

High School Students

During high school, students develop more sophisticated ideas about the mechanism of condensation at a molecular level and the cycling of matter, such as water, through ecosystems. They learn how matter moves around Earth in simple and complex molecules in vapor, solid, and liquid form and that the movement of matter is driven by the internal and external energy of Earth. Knowledge of heat, change in state, evaporation, condensation, and the force of gravity helps students understand why the water cycle occurs. However, do not assume that students have a correct conception of processes such as evaporation and condensation. Before more complex ideas are taught in high school Earth science, this probe is useful in determining whether students have progressed beyond their preconceptions about where water goes after it evaporates and how it can reappear as a liquid.

Response A intentionally does not use the term water vapor, because students may choose this answer without knowing that water vapor is one of several gaseous substances that make up air. This probe scenario can be demonstrated to students if there is enough humidity in the classroom. Be aware that some students who live in dry, desert areas may not have experienced this phenomenon to the extent that students in warm, humid areas have. Consider having students draw a picture to support their explanation. When using this probe with elementary school students who may be unfamiliar with atoms and elements, consider whiting out the last distracter. This probe can be combined with “What Are Clouds Made Of?” (p. 155) and “Rainfall” (p. 171) from this volume and with “Wet Jeans” from Volume 1 of this series (Keeley, Eberle, and Farrin 2005) to make up a cluster of water cycle–related probes.

• Before students can explain the process of condensation, they need to know where the water that condenses comes from. Research has shown that students seem to transit a series of stages in their understanding of evaporation. At first, they may seem to think that when water evaporates, it simply ceases to exist. In the next stage, they may think it changes location but that it changes into some other form we can perceive, such as fog, steam, or droplets. Fifth grade is about the time that students can accept air as the location of evaporating water, if they have had special instruction that targets this idea (AAAS 1993).
• In a study of Israeli children ages 10–14 (Bar and Travis 1991), children were asked what causes water to form on the outside of a container holding ice. The most frequent responses were “the coldness changed into water” or “the cold caused hydrogen and oxygen to change into water.” The researchers concluded that even though students knew that water as a gas (vapor) could be changed back to a liquid, applying that knowledge was difficult for students (Driver et al. 1994).
• In Osborne and Cosgrove’s (1983) study of New Zealand children’s ideas about change in state, they found that the percentage of students who could explain condensation as resulting from water in the air increased from 10% in children below age 12 to 55% in children ages 12–17. The majority of students gave macroscopic descriptions of condensation with very few mentioning energy and movement of molecules (Driver et al. 1994).

American Association for the Advancement of Science (AAAS). 1993. Benchmarks for science literacy. New York: Oxford University Press.

American Association for the Advancement of Science (AAAS). 2007. Atlas of science literacy. Vol. 2, “weather and climate,” 20–21. Washington, DC: AAAS.

Driver, R., A. Squires, P. Rushworth, and V. Wood- Robinson. 1994. Making sense of secondary science: Research into children’s ideas. London and New York: RoutledgeFalmer.

Gilbert, S. W., and S. W. Ireton. 2003. Understanding models in Earth and space science. Arlington, VA: NSTA Press.

Keeley, P. 2005. Science curriculum topic study: Bridging the gap between standards and practice. Thousand Oaks, CA: Corwin Press.

National Research Council (NRC). 1996. National science education standards. Washington, DC: National Academy Press.

Robertson, W. 2005. Air, water, and weather: Stop Faking It! Finally Understanding Science So You Can Teach It. Arlington, VA: NSTA Press.

Smith, M., and J. Southard. 2002. Water is all around you. Science Scope 26 (2): 32–35.

• Elementary school students need concrete experiences to understand what happens to water during a change in state before developing the more sophisticated idea of a water cycle.
• Observing this or similar phenomena and posing the question “Where do you think the water came from?” should be a part of every elementary student’s science experience. For students who strongly believe the water came from within the container of ice cubes, confront their ideas with a sealed container of ice in which they agree that nothing can get in or out. Another way to confront them with their idea that the water somehow leaked out of the container is to freeze ice that has been colored with food coloring. As the ice melts inside the container and a pool of colored water collects inside the container, the condensation outside the container will be clear. Use this discrepant event to challenge their ideas and help them think through a new explanation.
• Do not assume that because students use words like evaporation and condensation they actually know what is happening. Develop the concept before giving students the technical term for the processes that make up the water cycle.
• Be aware that textbook and internet representations of the water cycle may contribute to the idea that evaporated water immediately goes up to the clouds or the Sun, rather than exists in the air around us. Many representations show upward arrows pointing to the clouds or Sun that may influence students’ thinking about condensation so that they do not recognize that condensed water on an object forms from the surrounding air that holds water vapor.
• Teaching about condensation in the water cycle involves several interrelated ideas that should be combined in instruction. These ideas include conservation of matter, phase change, and composition and nature of air. It is particularly important that students accept the idea of air being a substance that is made up of matter (including water) in a form we cannot see.
• Have students visually observe condensation. Place a container in a shallow dish of water. Place clear plastic wrap loosely over the dish and container with the edges sealed. Put a coin or some small weight in the middle of the plastic so it sags into the container and place the device in the sun. As the water warms, condensation will occur on the inside of the plastic and run down into the container. Have students draw diagrams to trace and explain how the water moved from the shallow dish to the sides of the plastic and into the container.