3.1

Current lessons

As of this writing, eight lessons have been completed and at least two more are planned. They are available at no cost online at www.lasertechonline.org. Some popular outreach activities have not been included because they exceed the allowable cost. For example, we have yet to easily create an acceptable kaleidoscope without purchased mirrors. Although we have seen instructions on the web using various substitute reflectors they have been difficult to make, for example cutting hard plastic with a craft knife, or produce inferior results. The current list of Dumpster Optics lessons is in Table 1. The STEAM lessons include art, as well as science, technology, engineering and math (STEM). (Figure 2)

Table 1.

Dumpster Optics Lessons

Figure 1.

Dumpster Optics logo

Figure 2.

Dumpster Optics STEAM activities. (Left) Polarized light art using packing tape, laptop and polarized sunglasses. (Right) Student work from "Seeing Color - Eyes and Art" lesson, "Homage to the Square".

The Dumpster Optics lessons have been aligned to the NGSS standards (Grade 1: 1-PS4 Waves and their Applications in Technologies for Information Transfer and Grade 4: 4-PS4 Waves and their Applications in Technologies for Information Transfer). Details are on the web site.

3.2

A typical lesson: Reflection of Light

The lesson was created to align with the science standards as well as in response to research showing that misunderstandings of the role of light in the visual system and can persist into adulthood.^5,6,7 The materials list is provided in the teacher notes, along with suggestions for alternate materials (Table 2). We describe this lesson because it is the one for which we have the most complete field-testing reports. However, all of the lessons have the same format, with PowerPoint slides for students, detailed notes for teachers and links to video demonstrations.

Table 2.

Materials needed for the Dumpster Optics reflection lesson

All activities include vocabulary necessary for understanding the lesson. In this case some of the terms should be familiar to fifth grade students, for example, "parallel" from fourth grade geometry. All words should be defined and discussed before the lesson (Figure 3). Vocabulary is reinforced as the lesson proceeds. Laser safety is introduced in any lesson using laser pointers.

Figure 3.

Vocabulary for the Dumpster Optics reflection lesson

This lesson begins with a "warm up" or reflection activity asking students to think about where light comes from and how they can see an object that is not itself emitting light. After students respond in writing to the prompt shown in Figure 4, the class discusses the sources of light striking the object and where the light goes after striking the object. Students are encouraged to think about how it is that they can see objects that do not emit light. We found that many students are very observant, noticing LED indicator lights and exit signs for example.

Figure 4.

Prompt for warm up writing activity

On the pre-survey given to two groups of students in 2014 and 2015 more than 90% of fifth grade students (and many of their teachers) asked which common objects reflect light replied "a mirror".⁷ The qualitative part of the reflection lesson is an attempt to show that anything you can see reflects light from sources in the surroundings into your eyes. Students work with a partner and are first asked if a rough object like a tennis ball reflects light. (In practice, we were unable to find white tennis balls and so used white ping-pong or plastic foam balls.) As always, students first predict what they will see when the ball is illuminated with white and red light. After making and recording their observations, they engage in class discussion on the topic, "Do you think this rough object is reflecting light?" (Figure 5)

Figure 5.

Do rough objects reflect light?

The next step is to devise a "reflection test", first by demonstrating with a mirror and flashlight that the light reflected from a mirror can be directed onto a table underneath where it illuminates the table with a bright spot of light. After observing that the rough ball does indeed reflect light onto the table students are given a bag of assorted household items-paper, cloth, plastic spoons, finished and unfinished wood, cardboard, etc. and asked to classify them as shiny, rough or dull. (Some items might go into more than one category.) Students then predict if each object will reflect light and then perform the "reflection test". (Figure 5) Results are discussed as a class. If a team of students finds that an object does not reflect light they are requested to try the test again to be sure. They are also invited to add their own items to test. By the end of the first set of activities, students should be convinced that everything they see reflects light. (Figure 6)

Figure 6.

Students test a variety of materials to see if they reflect light onto the table.

The quantitative part of the lesson uses a laser pointer and begins with a discussion of laser safety. From the teacher notes,

To avoid having to locate small rectangular mirrors and then attach them to blocks to make them stand upright, the instructions specify CD jewel cases with the front side lined with black paper. The "mirror" will stand vertically when it is partially opened. Printable protractors can be found easily with an internet search. Students may need a refresher on how to measure angles. Students are asked to make a prediction before measuring the reflected angle and for each incident angle students record and then discuss their results and to determine if they agree. If there is disagreement, students can offer some reasons for the discrepancy. One common error is to be careless with the placement of the reflecting surface on the zero line of the protractor. After several angles have been measured, students are asked to make up a rule for reflection. The PowerPoint slide show includes animations illustrating the law of reflection and the difference between reflection from a mirror and from a rough surface. (Figure 7)

Figure 7.

Instructions for determining law of reflection. The graphic (and the two slides following, not shown) are animated.

The lesson also includes optional applications of the law of reflection that require more expensive materials or include the concept of imaging. For example, "Who can see the teddy?" uses a long mirror (the type sold for walls or doors) and asks which of several students placed in front or to the side of the mirror can see the reflection of an object held by the teacher. The optional application activities can be used to test student knowledge of reflection.

4.1

Classroom field-testing

All of the individual activities have been used either in classrooms (including high school and college where deeper learning is expected) or outreach, and most of the lessons have also been classroom tested. During the 2014-2015 academic year, six Connecticut fifth grade classrooms (123 students) participated in field-testing of the reflection lesson. A 3- question pre-test was administered two weeks before the lessons and post-testing took place 2 weeks and again 6 weeks afterward. As reported in Magnani and Donnelly⁸ students showed moderate improvement in understanding reflection after completing the Dumpster Optics lesson. We were surprised, however, that on the first post-test only 28% of students answered that light is reflected by all objects in a list (compared to 8% on the pre-test). In their written comments, many students remarked that they were surprised to learn this fact about light so it was odd that so few answered the question correctly. We repeated the question on pre- and post-tests in the 2015-2016 school year and found similar results. After discussion with elementary education experts we conclude that the question is not worded correctly for students who are novices at multiple-choice questions and that their written comments are a more reliable indicator of understanding. In addition, some students may have a lower reading comprehension level which may impact their understanding of the question.

4.2

Workshops

Although SPIE has sponsored hands-on PHOTON Explorations workshops for many years (often with the title "Optics Outreach Magic"), the first official Dumpster Optics workshop was held with SPIE support in July 2015 at ETOP (Education and Training in Optics and Photonics) in Bordeaux, France. The ETOP workshop was the first to encourage attendees to bring their school-aged children. We noted that adult participants seemed to be more willing to try the simple activities with their children than working alone in previous all-adult workshops. In August 2015 a second Dumpster Optics workshop was held at SPIE's Optics and Photonics conference in San Diego, CA. O&P participants gave helpful suggestions for organizing the materials to allow more time for experimentation with less time spent passing out supplies. Future workshops will feature materials packed in individual bags for easy distribution. (Figure 8)

Figure 8.

Materials for five Dumpster Optics activities packaged in individual labeled lunch bags.