3Tech4 2013 - Sunsational Sunprints - Tyler - Final-Printed

Sunsational Sunprints Overview In this exciting activity, campers will learn about UV light, sun safety and light sensitive reactions. Campers will get the chance to make their own picture using sun sensitive paper.

Topic (s) Chemistry, Biology Grade Level 3-4 Cost (per camper) $0.42/camper Time (preparation and activity) 1 hour Complexity Easy

Ontario Curriculum Links

Understanding Matter and Energy: Grade 4 - Light and Sound

Big Ideas:

● Light and sound are forms of energy with specific properties ● Sound is created by vibrations ● Light is required to see ● Technological innovations involving light and sound have an impact on the environment

Specific Expectations:

● assess the impacts on personal safety of devices that apply the properties of light and/or sound ● follow established safety procedures for protecting eyes and ears ● investigate the basic properties of light ● use scientific inquiry/research skills to investigate applications of the properties of light or sound ● use appropriate science and technology vocabulary, including natural, artificial, beam of light, pitch, loudness, and vibration, in oral and written communication ● identify a variety of natural light sources and artificial light sources ● distinguish between objects that emit their own light and those that reflect light from other sources

of 7 ESQ Activity Write-Up 2013 Sunsational Sunprints ● describe properties of light, including the following: light travels in a straight path; light can be absorbed, reflected, and refracted ● describe how different objects and materials interact with light and sound energy

Theory & Background Information

Light is a type of energy that we can see. It travels very fast, approximately 300 000 km per second. Light travels in sinusoidal wave like patterns in a perfectly straight line (light rays). Different types of light are defined by their specific wavelength. The wavelength of light is determined from the distance the light must travel to complete one wave cycle (see fig. 1).

Fig. 1: Light wavelength

Four properties of light are as follows: ● Light travels in straight lines as long as it is traveling in the same medium (I.e. air) ● Light travels in waves ● Light travels at the speed of approximately 300 million metres per second

When light waves hit a surface they will be transmitted, absorbed, refracted (bent) or reflected. Visible white light contains all the colours of the spectrum. The colours of the spectrum are red, orange, yellow, green, blue, indigo and violet. These can be remembered using the acronym: ROY G. BIV. White light can separate into these colours when it passes through a prism. Each of the colours of the spectrum has a different wavelength that is bent at a different angle when passing through a prism. This results in the differentiation of colour. Colour results when some wavelengths are absorbed and others are reflected. The colours that are reflected are the ones that we see. Black is seen when all wavelengths

of 7 ESQ Activity Write-Up 2013 Sunsational Sunprints of light are absorbed. White is seen when all wavelengths of light are reflected. When light waves hit certain smooth surfaces, they can reflect completely, and this results in a mirror effect. Mirrors are basically glass with a metal-coated back. When mirrors are placed in a combination, light waves can bounce back and forth creating multiple images.

Chemistry is the study of matter (made up of atoms) and its interaction with other matter. Substances can react with other substances in different ways depending on the type of matter they’re composed of. When we talk about reactions, substances can either undergo physical or chemical reactions. A physical reaction results when a substance changes its physical state (i.e. solid, liquid or gas). This means that the matter has NOT changed in the reaction but rather the matter is structured a different way. In contrast, a chemical reaction takes place when two or more substances (also called reactants) are mixed together to form a new substance (also called a product). This means that the “matter” involved in the reaction HAS changed into something new and is different from either of the initial reactant. Some signs of chemical reactions are: the forming of gas/bubbles, a temperature change, and the formation of a precipitate (something solid emerges from two liquids). Baking a cake is a good example of a chemical reaction that is easy for young children to understand. A very common example of a chemical reaction is baking a cake. You mix (eggs, butter, sugar, flour and water) together add heat from the oven and in no time you have a new product, a cake. The ingredients of the cake are the chemicals and the heat of the oven causes a chemical reaction to occur, which produces a cake which is a new substance different from the initial ingredients.

Some chemicals are said to be light sensitive, or photo-sensitive. These chemical may undergo light sensitive reactions when exposed to sunlight. This will occur as the sunlight excites the molecules in the substance, and causes the reaction. Engineers have taken advantage of this property of many substances in the design of machines that are powered by cars (solar powered cars, solar panels).

Another important concept to this activity is shadows. The sun’s rays travel in waves to the earth’s surface, but as long as the medium stays the same, these rays travel in straight lines. However, if the rays are blocked by an object that “absorbs” the rays, rather than “transmitting” them, the rays that are absorbed will stop at the object while those around the object will pass by the object and reach the ground. This leads to a pattern of light and dark areas on the ground in the shape of the outline of the object blocking the sun. This is illustrated in the diagram below (Fig. 2):

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Materials

Per Camper: ● 1 piece of Sunprint paper ● objects found outside (i.e. leaves, pine cone, etc.) Per Camp: ● several bottles of different types of sunscreen (SPF 5, 15, 20, 60) ● large flat container for dunking sunprints ● 16 small medicine cups for holding each type of sunscreen (4 stations of each SPF value of sunscreen) ● 32 cotton swabs (2 per medicine cup)

Safety Concerns

Camper should not eat the sunscreen.

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Applicable MSDS N/A

Risk Factors ● Sunscreen should not be ingested by anyone, ever!

Location ● Lesson will take place in our camp room, we will then move outside for campers to make our designs, place paper in the sun and set the image with water.

Emergency Contingency Preventative 1. Ensure campers understand that sunscreen is not to be eaten.

Reactive 1. Sunscreen is considered only minimally toxic. It is considered a minor irritant to the stomach and intestines. Should a camper ingest sunscreen, their health should be monitored. Should they experience upset stomach, poison control should be called.

Procedure Preparations 1. Small amounts of sunscreen should be placed in small medicine cups with cotton swabs, such that groups of 4 campers have access to each type of sunscreen.

Introduction 2. Ask the class what some sources of energy are? a. Prompt them to answer with the sun 3. Ask the campers what type of energy the sun provides us with? a. Several answers are acceptable here, including light, heat, solar power, etc. 4. Now explain that light is a type of energy. 5. Ask the campers for some properties of light? a. Light travels in straight lines, light travels in waves, light travels really quickly (300 000 km/sec). 6. Now ask the campers the campers for some different uses of light? a. We use light for vision, plants use its energy to grow, we harness light energy in make electricity (solar panels) and light can be used to drive some chemical reactions. 7. What is a shadow? a. A shadow is an area where the sunlight can’t shine because it is blocked by an object.

of 7 ESQ Activity Write-Up 2013 Sunsational Sunprints 8. What shape is a shadow? a. A shadow is the shape of the object that creates it. 9. Draw a diagram on the board that is similar to Fig. 2. Indicate that the rays that hit the tree are absorbed, while those that go around hit the ground. The result is a shadow that takes the shape of the tree. 10. You could test the campers now by taking an object from the camp room and asking what shape its shadow would be. a. It should be the shape of the shadow. To extend this section of the lesson, it could be illustrated how the location of the light source will affect the shadow shape. 11. Finally, ask the campers what they must apply to their skin to make sure they don’t get a sunburn. a. Sunscreen! (It’s like a permanent shadow for your skin) 12. When applying sunscreen it’s very important that you don’t miss any spots. If you do, you will get burned in the spot you missed, as there is no sunscreen there! 13. Next, explain that sunscreen always has a number associated with it. This is the SPF number. This stands for the sun protection factor. The SPF number is a multiplication number. So, SPF 30 sunscreen provides 30 times the sun protection than your skin alone. a. This may also be illustrated by using the time spent outside before a burn. So, if you can normally stay out for 10 minutes before a burn, SPF 30 sunscreen would allow you to stay out for 300 minutes before getting a burn. 14. In today’s activity we are going to make permanent shadows, using our special light sensitive paper.

Activity 1. Take the campers outside and allow them to collect 2 articles that they think would make a neat design on their paper. We don’t want to damage the wildlife, so only leaves/twigs on the ground should be used. 2. Now give the campers their paper, do this in a shady spot! 3. The campers will then be given a chance to draw a design on their paper using sunscreen. This will be present in the medicine cups, as described in the Materials section. 4. Once this is done, the campers should lay their paper in the sun and leave it to set for about 5 minutes. 5. Once the paper has faded from blue to white (the part of it that is exposed to the sun), its done! 6. Remove any leaves/twigs etc, and take the paper to the basin of water. Rinse off the sunscreen and allow the paper to sit until the colours reverse (blue to white and vice versa). When this is done (about 2 mins), the image will be permanent! 7. Move back to the camp room and put our sunprints in our bags.

Activity Accommodations and Extensions Accommodations

of 7 ESQ Activity Write-Up 2013 Sunsational Sunprints The lesson may be shortened to exclude the information on sunscreen. We could also not use sunscreen to create shadows, but instead only use objects to cast shadows. Campers with restricted mobility may do this inside by a window.

Extensions Campers should be asked why several types of sunscreen were used? This was because sunscreens of different SPF values should cause shadows of varying darkness. Can they design a simple experiment to demonstrate this?

Safety Considerations Make sure campers don’t eat sunscreen. As this activity must be done in the sun, sunscreen should be worn so no one gets a burn!

Templates N/A

Safety Templates N/A

Resources ● Past ESQ writeups, “Sunprints”, Suzuki A, 2004 ● How sunscreen works, http://chemistry.about.com/od/howthingsworkfaqs/f/sunscreen.htm

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