Sun and shadow

Author: Drs. Frans van Galen

This example is part of a learning trajectory for guiding students (Grade 5-7) as they develop concepts about shadows. In the exploratory part of the activity, the students experience that the shadow of a stick becomes shorter as the morning progresses and it becomes longer by the end of the afternoon. One challenge is to try to explain why the shadow changes in length. Students can study this phenomenon using the computer program. This discussion involves concepts such as angles, length, and direction.

The activity can be performed outside on a clear and sunny day. Otherwise the computer program can be used straight away. The students start outside the classroom with predicting how their shadows change during a short period of time. Back in the classroom, the students can discuss their ideas by drawing pictures of how the shadow of a stick would change throughout the day. Finally, the students can test their predictions either by going outside with a stick, or by using the computer program that can be found on the website. The website includes handouts that accompany the program, as well as a grading scale for the teacher to evaluate the students’ performance. Finally, students are encouraged to discuss their findings.

Pedagogical issues

The teacher’s role is to guide the students’ exploration process and discussion. The students are encouraged to explore the behavior of shadows outside as the day progresses. This involves making predictions. As the students test their predictions using the computer program, the teacher must be sure to guide the students’ inferences to conclusions. Meanwhile, the teacher can also add more mathematical concepts such as angle, direction, and length to the students’ discussions.

Characteristics

Open activity based on the opportunities for students to explore the.

Potential for PD

This activity could be used as PD-activity because it covers the entire spectrum of what is involved in scientific thinking. The challenge for the teacher is to first guide the students through the exploratory phase, then to the predicting phase, and later to drawing conclusions.

Commentary

The activity is designed for the project “Techplek op het RekenWeb”, financed by VTB. The idea behind this project is to give students the opportunity to ask fundamental questions such as “why does it become dark at night” or “ why does a shadow change during the day”. The activity has proven its efficacy in the way that it has been published in didactics journals and that teachers regularly consult the website for the activity’s materials. It relates to IBL in how students are encouraged to explore, predict, and test their inferences about mathematical and scientific phenomena. For example, the questions that introduce the students to the activity are: how do shadows change during the day, is the length of your shadow the same in the winter as in the summer, and does the sun really rise in the East and set in the West? It can be classified as an interdisciplinary activity as it involves measuring, thinking about directions, movement and angles, and reasoning about scientific concepts such as the sun’s trajectory and seasons.

Links

Literature: Van Galen, F., Jonker, V., & van Velthoven, W. (2006/2007). Zon en Schaduw. De Realiteit en de Computer (Sun and Shade. Reality and the Computer). Volgens Bartjens…,26 (2). 16-18
Website: Techniek Basisonderwijs. Science and technics in primary education (in Dutch)
Website: Techplek op het RekenWeb. Mathematics and technics in primary education (in Dutch)

Last change: 8 november 2011

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