Water is a commonly used example of the solid, liquid, and gaseous states of matter. The properties of these states, along with the phase changes between them, are complex and easily misunderstood. The water cycle, too, is a subject with great potential for misconceptions among students and adults alike.
In this article, we’ve listed some common misconceptions that researchers tell us students may hold about states and changes of matter as well as the water cycle. This list is meant to stimulate your thinking about the ideas your students bring to the classroom.
It may also be helpful to consider weather-related misconceptions, as precipitation is an important part of the water cycle. For more information on weather misconceptions, please see “Common Misconceptions about Polar Weather and Climate” in Issue 4.
We’ve also included formative assessment probes, which are modeled (with permission from NSTA Press) after those found in Uncovering Student Ideas in Science, Volumes 1, 2, and 3, as well as lessons and activities to shape students’ understanding of these concepts.
Misconceptions About States and Changes of Matter (Water)
|Students may think…||Instead of thinking…|
|When water boils and bubbles, the bubbles are air, oxygen or hydrogen, or heat.||Bubbles formed by boiling water consist of water vapor (steam).|
|Steam is hot air.||Steam is water vapor.|
|When steam is no longer visible it becomes air.||When water vapor condenses in the air it is visible as tiny water droplets.|
|Water in an open container is absorbed by the container, disappears, changes into air, or dries up and goes into the air.||Water in an open container evaporates, changing from a liquid to a gas.|
|Ice molecules are colder than water molecules.||Ice molecules have less kinetic energy than water molecules.|
|Condensation is when air turns into a liquid.||Condensation is water vapor in the air that cools enough to become a liquid.|
|Condensation on the outside of a container is water that seeped (or sweated) through the walls of the container.||Condensation of water vapor happens when the water vapor in air comes in contact with a cool surface.|
|Expansion of matter is due to the expansion of the particles rather than increased space between the particles.||Matter expands when heated because the molecules are vibrating more quickly, loosening bonds, and increasing the space between adjacent atoms or molecules.|
Misconceptions About the Water Cycle
Younger students tend to understand the water cycle by focusing on the properties of water. They see the water cycle primarily in terms of freezing and melting. These concrete thinkers also have a difficult time with the idea of conservation of matter in terms of water vapor and air, making evaporation and condensation particularly difficult concepts. Additionally, students may understand the water cycle on a local level and not generalize the concept to a global scale or may not understand that water has been conserved throughout time.
|Students may think…||Instead of thinking…|
|The water cycle involves freezing and melting of water.||The water cycle involves evaporation of liquid water, condensation of water vapor, and precipitation (rain, sleet, hail, or snow).|
|Water only gets evaporated from the ocean or lakes.||Water can evaporate from plants, animals, puddles, and the ground in addition to bodies of water.|
|The water cycle only includes rain and snow.||Ice in all its forms (sea ice, glaciers, ice sheets, icebergs, permafrost) is part of the global water cycle.|
What causes these misconceptions?
In general, misconceptions result from students creating their own explanations for how the world works. Often, these ideas are formed well before a student arrives in science class – and serve their purpose well. Numerous studies and anecdotal evidence show that students cling to these ideas even in the face of discrepant events and explicit instruction.
However, some of the misconceptions regarding states and changes of matter can actually be viewed as part of a developmental process. As children age, they are better able to understand states of matter, particularly the more abstract concept of a gas. Students also develop over the years a better understanding of the conservation of matter like water and air. This increasing sophistication of ideas over time should reassure teachers who find that, despite their best instructional efforts, their elementary students still do not fully understand these concepts.
Finally, language and diagrams used in conversation and in textbooks can also lead to misunderstanding. For example, we often say that cold objects like cans of soda “sweat.” Students may hear this description and relate it to their understanding of how humans sweat, causing them to think that the moisture found on the can’s surface actually has come from inside the can and not from the water vapor present in the air. Diagrams of the water cycle in textbooks often show evaporation occurring over a large body of water, such as an ocean. The absence of other arrows indicating evaporation from living things, puddles, and the ground may lead to an incorrect conclusion about where evaporation occurs. It is important for teachers to reflect on how their use of language or diagrams may inadvertently lead to misconceptions.
Probing For Student Understanding
Even if some misconceptions about states and changes of matter and the water cycle are to be expected in the elementary grades, it is still important for teachers to take the time to assess student understanding and the preconceived ideas they bring to science class. Simply observing students, asking questions, and paying close attention to their drawings and writings may be sufficient to gauge students’ ideas. However, more formal assessment tools may also be helpful.
Volumes 1, 2, and 3 of Uncovering Student Ideas in Science each contain 25 formative assessment probes to help teachers identify misconceptions. Each volume of this series contains several probes that relate to states and changes of matter and the water cycle.
Related formative assessment probes in Volume 1 of Uncovering Student Ideas in Science:
“Ice Cubes in a Bag” asks students to decide whether there will be a change in mass when ice changes to liquid water. It elicits student ideas about conservation of matter in the context of substances and change in state.
“Is It Melting?” asks students to select situations that involve melting as opposed to other physical or chemical changes. It elicits student ideas about the physical process of melting.
“Wet Jeans” asks students to explain why a pair of jeans dry on a clothesline. It elicits student ideas about where water goes right after it evaporates.
Related formative assessment probes in Volume 2 of Uncovering Student Ideas in Science:
“Turning the Dial” asks students to decide if the boiling temperature of water will change with more or less heat. It elicits student ideas about boiling point.
“Boiling Time and Temperature” asks students to decide if the boiling temperature of water will change over time. It elicits student ideas about the characteristic property of boiling point.
“Freezing Ice” asks students to decide if the size of an ice cube affects the temperature at which the water freezes. It elicits student ideas about freezing point.
“What’s in the Bubbles?” asks students to explain what is in the bubbles of boiling water. It elicits student ideas about the change in state of boiling water.
Related formative assessment probes in Volume 3 of Uncovering Student Ideas in Science:
“Is It a Solid?” asks students to decide which materials are solids. It elicits student ideas about the properties of solids.
“What Are Clouds Made Of?” asks students to explain what clouds are made of. It elicits student ideas about clouds.
“Where Did the Water Come From?” asks students to explain why condensation forms on a container of ice cubes. It elicits student ideas about condensation.
“Rainfall” asks students to explain how rain falls from clouds. It elicits student ideas about precipitation.
In addition, we’ve followed the model used by Page Keeley and coauthors in the three volumes of Uncovering Student Ideas in Science (© 2005-2008 by NSTA Press) and created a similar probe to elicit students’ ideas about the conservation of water through the global water cycle.
How Much Water?
This formative assessment probe is designed to assess student misconceptions about conservation of water and the water cycle.
Teaching the Science
While identifying student misconceptions is fairly straightforward, creating conceptual change is not. Researchers recommend using a hands-on approach and providing adequate time and repeated activities to create the conditions necessary for conceptual change. However, it is important to understand that children may be quite resistant to change even when these suggestions are carefully followed. In some situations, researchers found that students developed two parallel explanations for scientific events: one for science class and one for the “real world!” Instead of becoming discouraged, teachers should be aware of the ideas that students bring with them to science and how these might influence instruction and learning.
It is also important to remember that some of the misconceptions regarding states and changes of matter may be appropriate for students’ current developmental level. While concepts such as evaporation and condensation may be introduced in the elementary grades, teachers should remember that students will develop an increasingly sophisticated understanding over the years and that complete mastery of these concepts is not to be expected at this point.
For lessons and activities about the water cycle and states and changes of matter, please see “The Water Cycle and the Polar Regions: Hands-On Science and Literacy” in the Science and Literacy department of this issue. Integrating nonfiction text and children’s literature may also help students with these more abstract concepts.
National Science Education Standards
Assessing and targeting student misconceptions about states and changes of matter and the water cycle meets the Physical Science Content Standard and the Earth and Space Science Content Standard of the National Science Education Standards.
Henriques, L. “Children’s misconceptions about weather: A review of the literature.” National Association of Research in Science Teaching annual meeting, New Orleans, 29 April 2000.
Copyright August 2008 – The Ohio State University. This material is based upon work supported by the National Science Foundation under Grant No. 0733024. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. This work is licensed under an Attribution-ShareAlike 3.0 Unported Creative Commons license.