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

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The purpose of this assessment probe is to elicit students’ ideas about seasons. The probe can be used to determine whether students recognize the effect of the Earth’s tilt on its axis and the resulting intensity of sunlight as the reason for seasons.

Friendly Talk

Earth-Sun system, seasons

The best response is Raul’s: It’s because Earth’s tilt changes the angle of sunlight hitting Earth. Seasons are primarily caused by the 23.5- degree angled tilt of Earth’s axis as it revolves around the Sun in a slightly elliptical orbit (almost circular). This 23.5-degree angle varies slightly over time between 22.2 and 24.5 degrees. As Earth revolves around the Sun, this tilted axis always points in the same direction. This means that during part of the year one hemisphere will be leaning or bending more away from the Sun, which results in winter, and the other hemisphere will be leaning or bending more toward the Sun, which results in summer.

What does this have to do with summer being warmer? The tilt affects the intensity of sunlight striking Earth in different locations. When a hemisphere is tilted away from the Sun in the winter, the rays from the Sun strike this part of Earth at a lower angle that spreads the sunlight over a larger surface area. Therefore, some regions receive less heat, such as the Northern Hemisphere during winter. When it is winter in the Northern Hemisphere, the Southern Hemisphere is experiencing summer because the Southern Hemisphere is tilted toward the Sun. The sun strikes Earth at a higher angle during the summer, which concentrates Earth’s energy so it is less spread out. This increases the intensity of sunlight and thus warms the surface more. In the other half of Earth’s orbit (half a year later) the situation reverses itself and it becomes summer in the Northern Hemisphere as the north pole is tilted toward the Sun and the south pole is tilted away, resulting in winter. In addition, during the summer, the Sun stays above the horizon longer, providing more time for the Sun’s energy to heat that region of Earth.

Sunlight is most concentrated near the equator because of the more direct rays of the Sun. The number of hours of daylight and hours of darkness are almost the same. This unchanging angle of sunlight and consistent daytime and nighttime results in a year with minimal seasonal change.

Many people think the reason for the seasons is the Sun’s closer proximity to Earth in the summer than in the winter. It is true that at times in Earth’s slightly elliptical orbit we are closer to the Sun. However, we are actually closer in the winter than in the summer; thus distance is not a reason for why it is warmer in the summer. The Earth is closest to the Sun on January 4 and farthest away from the Sun in July, when we have our Fourth of July barbeques.

Elementary Students

In the elementary school grades, students learn about the four seasons and the changes that happen during each season. The focus is on observations, not explanations of what causes the seasons, an idea that is much too complex for this grade level.

Middle School Students

Students at this level begin to develop understandings of the Earth-Sun system, including how Earth orbits the Sun and the role of sunlight in heating Earth. However, explaining what causes the seasons is still very difficult at this age because of the complex spatial reasoning required to understand the seasons. Nevertheless, an explanation is introduced at this grade level, though it may not be until high school that students can fully comprehend it.

High School Students

At this level, students’ understanding of orbital geometry is more developed and enables them to better understand the reason why we have seasons. Their quantitative understanding of the intensity of light based on the area of light striking a surface helps them understand how the angle of sunlight reaching different parts of Earth results in the warming that produces seasonal variations. Because the idea of seasons is so difficult to learn at earlier grades, it is recommended that it be revisited in high school.

This probe is best used at the middle or high school level to determine students’ misconceptions about seasons before instruction.

• Students of all ages (including college students and adults) have difficulty understanding what causes the seasons (AAAS 2007).
• Studies by Sadler (1987) and Vosniadou (1991) show that students may not be able to understand an explanation of the seasons until they can reasonably understand the relative size, motion, and distance of the Sun and Earth (AAAS 2007).
• Atwood and Atwood (1996), Dove (1998), Philips (1991), and Sadler (1998) found that many students up through preservice believe that winter is colder than summer because the Earth is farther from the Sun in the winter. This belief persisted even after instruction in Earth science (AAAS 2007).
• Researchers have attributed students’ thinking that it is warmer in summer time because the Earth is closer to the Sun to their conception of an elongated elliptical orbit which makes it appear as if the Sun is closer to Earth during certain times of the year (Sadler 1998).
• Galili and Lavrik (1998) found that students’ ideas about how light travels may interfere with their understanding of the seasons.
• Some students confuse Earth’s daily rotation with its yearly revolution around the Sun (Salierno, Edleson, and Sherin 2005). For example, they believe that the side of Earth not facing the Sun experiences winter (AAAS 2007).
• Baxter (1989) noted age-related trends in children’s alternative conceptions related to seasons. The most common conception in children up through the age of 16 was that the Sun is farther away in the winter. This was consistently prevalent across ages and particularly pervasive in the 9–12 age range. Up to age 10, a small number of students think changes in plants cause the seasons. This number increases between the ages of 10 and 12. A small number of students up to ages 9 and 10 think winter clouds stop the heat from the Sun. This idea increases slightly between ages 10 and 14. Up until age 12, some students think the Sun moves to the other side of Earth. By age 12, this idea seems to go away (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., and S. 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.

Philips, W. C. 1991. Earth science misconceptions. Science Teacher 58 (2): 21–23.

Plait, P. 2002. Bad astronomy: Misconceptions and misuses revealed. New York: John Wiley and Sons.

• Students need to understand Earth’s orientation in relation to the Sun and how sunlight strikes the Earth before they can develop explanations for the seasons.
• When teaching about the shape of Earth’s orbit, the word ellipse can be confusing to most students and to some teachers. For many, ellipse means a highly oval-like orbit and they do not recognize a circle as being a special ellipse (just like a square is a special type of rectangle). Once they realize a circle as a special ellipse, they are more accepting of ellipses that are almost indistinguishable from circles.
• Be aware that textbook representations that show an exaggerated elliptical orbit can reinforce the idea that the Earth is closer to the Sun during parts of the year. Explicitly point out these flaws to students and show why an exaggerated ellipse is used in representations. An analogy you can use is to hold a glass or cup so you are looking straight down into the glass and the rim will look like a circle. Next hold the glass or cup out in front of you slightly below the level of your eyes. Now when you look at the rim it looks like an exaggerated ellipse. The rim did not change. The only thing that changes was your viewing plane. Relate this to the view in textbook representations.
• The PRISMS website, a National Science Foundation–funded National Science Digital Library project, provides reviews of representations and phenomena used to teach the seasons. These can be accessed at http://prisms.mmsa.org.
• Select carefully designed curricula to teach the reasons for seasons. The Great Explorations in Math and Science (GEMS) unit The Real Reasons for Seasons and Project ASTRO have lessons developed to address commonly held ideas (Gould, Willard, and Pompea 2000; Fraknoi 1995).
• Use models to show how the angle of sunlight affects how much surface area a given amount of light covers. Relate light energy to heat, demonstrating how the same amount of heat in a less spread-out area warms a surface more than the same amount of heat that is more spread out.
• Obtain images of the Sun taken at different times of the year from the same location and camera position (see NASA Sun- Earth resources at http://sunearth.gsfc.nasa. gov). Enlarge the images using the same percentage of enlargement. Students can use the enlarged images to measure the Sun’s diameter and make the link between increased diameter and closer distance to Earth. Students will find that the diameter of the Sun in winter is slightly more than in summer, thus dispelling their notion that the Sun is closer to Earth in the summer. This contradiction of their belief that the Sun is closer in the summer encourages students to think and seek out what a possible explanation could be.
• Kinesthetic Astronomy, from the Space Science Institute in Boulder, Colorado, is a good resource for modeling seasons. It can be downloaded free of charge at www.spacescience.org/ education/extra/kinesthetic_astronomy/index. html.