PROFILES Teaching Material Material for Teachers

Transcription

1 Instructions for the task Magic Pictures PROFILES Teaching Material Material for Teachers In an experiment, the students create magic pictures. The phenomenon of magnetism can be made visible by means of these pictures. The scientific background of the pictures is identified with the help of the teacher. The magic pictures provide the students with an aesthetic approach to technology. The experiment on magic pictures can be linked to the topic of magnetism. It is suitable as an introduction or as a conclusion. Social form: in class: procedure of experiment, demonstration of material for the experiment, preliminary discussion of tasks pair work: conduct experiment, solve tasks in class: securing knowledge about tasks Group formation: Individualization: Extension: pairs: girls only and boys only the following tasks can be distributed among the group members: conduct experiment take photographs (best to do in pairs: one person holds magnifying glass, other person takes photographs) write comments on the individual steps The teacher makes sure that the students take turns in their activities. The students may conduct the experiment on magic pictures several times. Presentation of photographs As homework, the students show the photographs to a chosen person. They comment on the pictures from three different perspectives: aesthetic perspective: comment on the photos from an artistic perspective. technological perspective: explain how the pictures were created. scientific perspective: explain how the spiky structure of the ferrofluid and the labyrinth effect have been brought about. Back at school, the experiences gained through the homework are exchanged. Who was shown the photos? How did the observers react to the photos? What was easy to explain, what was difficult?

2 Material Source of supply Costs Ferrofluid (magnetic nano particles in a carrier substance): supermagnete.ch Fr. for 2 bottles 10 ml per bottle 2 to 3 bottles of ferrofluid are sufficient for one class Disposable gloves: made of latex to clean the ferrofluid from the glass plate with a paper tissue. shop 9.95 Fr. for 100 pieces; 2.50 for 10 pieces Magnets: cube magnet (15x15x8 mm, NdFeB, N42, nickelized) 10 cube magnets per class Protective glasses (normal glasses will also protect the eyes) Watercolors: tubes (e.g. for rustic arts) a maximum of 5 colors per picture, 5 to 10 colors per class Small palette for mixing colors made of plastic to dilute colors with water 1 per group Glass of water (or plastic cup): to dilute watercolors with water 1 per group, 10 per class Coffee stirrers made of plastic, to mix colors with water: 1 piece per color (approx. 5 pieces per group) Glass plate (cut to size or from picture frame): window glass (with smooth surface, easier to clean) 10 x 15 cm 1 per group, 10 per class Wooden wedges or plasticine: (to raise glass plate, wooden wedge: 13cm long, 2cm wide, 3cm high) Double faced adhesive tape: 1 roll per class kg / m supermagnete.ch DIY shop or school DIY shop or school DIY shop or school school 2.45 Fr. per piece; for 10 pieces Fr. per piece 2.75 Fr. per small tube; Fr. for seven tubes 9.50 Fr. for a packet of 10 shop 2.30 Fr. for 100 pieces DIY shop 9. Fr. for 10 cut to size window panes DIY shop DIY shop 2.95 Fr. plasticine 10. Fr.

3 Cardboard box, coated chipboard or solid core panel: (Cardboard box is very suitable. The magnet is fixed to the cardboard plate with double faced adhesive tape.) approx. format A4 1 per group, 10 per class stationary shop DIY shop 4. Fr. for cardboard box or 40. Fr. for solid core panel 0.15 Fr. per needle, 0.30 Fr. per syringe; 4.50 Fr. per class Syringe with needle for adding the watercolors to the drugstore ferrofluid needle: diameter x length: ideally 0.9 x 40 mm size of syringe: 1 ml 1 per group, 10 per class White paper (to be placed under glass plate): school cut to the size of the glass plate, 10 sheets per class Camera (smartphone, mobile phone with camera or digital students/teachers camera) 1 2 per group Magnifying glass: ideally a small fold up magnifier or a school larger hand magnifier for taking photographs of the magic pictures: magnifying factor: approx. 8x 10 per class Facial tissues or kitchen roll shop 1.00 Fr. per to wipe off pictures from the glass plate piece 1 or more boxes / rolls per class Newspapers as padding school Acetone and petrol: the oily ferrofluid can be wiped off drugstore/pharmacy approx with petrol. Acetone is suited for wiping off watercolors. Fr. Further optional material Material Source of supply Costs Magnets: Additionally, other types of magnets can be used. Always choose neodymium magnets, ferrite magnets are not strong enough. supermagnete.ch depending on number of magnets mm side length or diameter various thicknesses (1 mm 8 mm) various forms (cubes, round slices, rings) Scissors to cut white A4 paper to the size or the glass plate (teacher might do this). school 1 per group, 10 per class Desk lamp or torch (for taking photographs): 10 per class school/students

4 Color printer (to print photographs) school Projector (beamer or daylight projector; printed copies of school the photos are also possible, or photos on the smartphone display) Work clothes are not absolutely necessary, if the students work carefully. Due to its oily consistency, the ferrofluid cannot easily be removed from clothes. students Safety instructions a) Tip of syringe needle: The teacher has to alert the students to the sharp tip of the needle. Comprehensive safety instructions regarding the magnets and the ferrofluid are enclosed in the delivery and are displayed on the internet site supermagnete.ch. b) Bruises: The teacher has to warn the students not to get their fingers trapped between two magnets. Per group, the teacher fixes one magnet to the board (cardboard box, coated chipboard or solid core panel) with a strong double coated adhesive band. The magnets may attract scissors, watches and belt buckles. c) Explanation: Comparison for the adhesive force of the magnets used: The adhesive force of 76 N is comparable to a 7.6 kg stone, which is balanced on a fingertip. The teacher might bring a heavy stone to the classroom to illustrate the adhesive force. d) Formula for the (adhesive) force F = 76 N = m g = 7.6 kg 10 The pressure exerted by the magnet is high, because magnets have a high adhesive force and the skin of the trapped finger is a small surface. Formula for pressure p = = e) Allergy to nickel: The teacher checks if anyone is allergic to nickel. At the end of the experiment, students can wash their hands. f) Ferrofluid: If ferrofluid gets onto the hands, they ought to be washed with water and soap. The ferrofluid makes the skin turn darker. It is possible to wear gloves. Do not swallow. The ferrofluid causes stains on non smooth surfaces. Before using the ferrofluid in class, it is recommended to test, whether it can be removed from surfaces (e.g. sink) with petrol. g) Cardiac pacemaker: Magnets may influence the functioning of pacemakers. h) Metal splinters: If two magnets collide, they may splinter. Splinters may cause injuries to the eyes. Protective glasses have to be worn while handling large magnets. i) Magnetic field: The magnetic field may damage electronic devices, credit cards, mechanical watches and loudspeakers.

5 j) Protective glasses: The glasses offer protection from possible splinters from two colliding magnets and from possible discoloration of the cornea caused by ferrofluid getting into the eyes. k) Gloves: The gloves offer protection from a possible discoloration of the skin caused by ferrofluid and from a possible allergy to nickel caused by the coating of the magnets. l) General information: If the experiment is conducted for the first time, the teacher and the students may / should wear protective glasses and gloves. For further experiments, the teacher may assess whether or not protective glasses and gloves are necessary depending on the students skills.

6 Procedure: Time Activity Material 5' Introduction The teacher announces that something nice is going to be created in class. He/she tells the students, that they are going to be artists, technicians and scientists all in one. Moreover, the teacher arouses interest and excitement in the students by telling them that photographs of magic pictures can be taken home from class. Task sheet The students read the questions on the experiment of magic pictures before conducting the experiment. They answer the questions in writing. Student questions For the time being, the teacher leaves any questions the students may have unanswered during the experiment. Thus, the need of the students to explore the scientific background of the magic pictures is enhanced. The teacher may ask students to take down their questions regarding the experiment. task sheet 50' 1) Realization of the experiment a) Procedure The teacher shows the material for the experiment and briefly explains the procedure. The task sheet for the students regarding the realization of the experiment comprises instructions with the individual steps and an illustration of the experiment set up. b) Suggestions The teacher may provide students with the following suggestions: Clean syringe: Draw up and eject water in order to clean syringe and needle from a particular color. Air bubbles in needle: Softly tap the syringe with a finger so that the air bubbles rise up. Dilute watercolors: Students may try to identify the ideal dilution for watercolors. Distance between magnifier and camera: The magic pictures are enlarged for the photographs by means of a magnifying glass. The ideal distance between magnifying glass and camera has to be determined. Variety of magic pictures: The teacher may ask students to look at the magic pictures of other groups. see list of materials c) Variation of procedure The teacher asks the students to vary the procedure. The following

7 points can be varied: extent of diluting the watercolors with water ratio of amount of ferrofluid : watercolors (The students improve the ratio automatically) spot on the glass plate for adding the ferrofluid and the watercolors (the ferrofluid is drawn from the pipette, which is a fascinating moment) number of different watercolors and amount per color distance between glass plate and magnet (the glass plate can be slightly raised with the wooden wedges / the plasticine, which leads to a change in the size of the spikes of the ferrofluid or to a change in the labyrinth effect). 15' 2) Document procedure a) Photographs The students continually document the individual steps by means of a camera integrated in a smartphone or mobile phone. Via smartphone, the students take the photographs of the magic pictures out of their classroom into their world. For youngsters, the smartphone functions as a personal recorder. It can also function as a door opener for technological and scientific aspects. There may be students that do not have a smartphone or mobile phone. The teachers may lend them a digital camera, or they borrow a camera from someone they know. The digital camera provides a slightly better quality of the pictures than the smartphone does. b) Text The photos are commented on in writing. The students describe the procedure as well as the results of the individual steps as detailed as possible. What happens, for instance, when the ferrofluid is put on the glass plate? What happens after the watercolors have been added? How was the procedure changed and improved? task sheet smartphone / digital camera 10' 3) Artistic perspective The students note their thoughts regarding the color combination and pattern of the magic pictures: Do you like the picture? Are there combinations of colors that you particularly like? Which are your personal preferences? In how far can the pictures be reproduced? The following criteria for observing the pictures may be applied: associations, comparisons, analogies: e.g. patterns of textiles, aboriginal pictures, electronic chips magic picture

8 formalities, structures ( black and white observation: regular, cellular patterns ( labyrinth effect ) color contrast: e.g. complementary colors (such as green red, blue orange, purple yellow), which create tension but also enhance the unit color quality: pure colors (powerful, gaudy), dull colors amount of color: amount of a specific color 15' 4) Scientific explanation During the lesson, the teacher answers the students questions regarding the scientific background of the magic pictures. It does not matter if the teacher cannot answer a question. Either the teacher or the student will research for an answer. A question might also be left aside as an interesting question. It is typical for scientific experiments, that not all questions can be answered and that new questions arise during the experiment. task sheet The students note a scientific explanation for the labyrinth effect in their own words. The teacher asks some of the students to read their notes to the class. He/she appreciates the contributions and adds information if necessary. Then, the expert knowledge for the scientific explanation of the magic pictures is added. a) Spiky structure of ferrofluid The ferrofluid is an oil in which tiny magnetic particles float. One drop of ferrofluid is placed on the glass plate. A magnet is located under the glass plate. In the magnetic field, the ferrofluid forms spiky structures. The three dimensional structure is created by aligning magnetic fields in the tiny individual iron particles of the ferrofluid (see illustration below, which is also included in the students task sheet). Nanoparticles are approximately 50,000 times smaller than a hair s diameter. Iron is called ferrum in Latin and le fer in French, thus the word ferrofluid.

9 = glass plate = board = lines of magnetic flux = North Pole = South Pole = spiky structure of a ferrofluid in a magnetic field = magnetic iron particles (5-10nm/nanometer in diameter Illustration 1: spiky structure of a ferrofluid = oil b) Labyrinth Effect The watercolors are injected into the spikes of the black ferrofluid by means of a syringe. This results in colored strips, as the watercolors and the oil don t mix (see colored magic picture on the top right of this page and student s picture below). The colors form a cellular pattern which resembles a labyrinth, as the oil contains small magnetic particles. The magnet under the glass plate causes the iron particles in the ferrofluid to form a labyrinth like structure. In simplified terms, the magnetic iron particles in the oil attract each other and thus form threads, which then leads to the labyrinth effect. The magic picture is small; it is the size of a thumbnail.

10 Illustration 2: A student s magic picture. The black threads are made up of the ferrofluid, the colored structures were created with watercolors. The reproduction of the magic pictures is limited. The arrangement of the magnetic particles in the ferrofluid is coincidental. 20' 5) Discussion and cleaning up Discuss tasks number 2) and 3) in class and solve task number 4) with your teacher in class. Clean up your workplace: The teacher now asks students to clean up. The oil like ferrofluid can be cleaned off with petrol. Acetone is suitable for cleaning watercolors off items. The syringe needles have to be disposed of with their plastic protection put on. task sheet acetone, petrol

11 5' 6) Homework: present photographs As homework, the students show the photographs to selected persons. The comment on the photos from three different perspectives: aesthetic perspective: comment on the photos from an artistic perspective. technological perspective: explain how the pictures were created. scientific perspective: explain how the spiky structure of the ferrofluid and the labyrinth effect have been brought about. Back at school, the experiences gained through the homework are exchanged. Who was shown the photos? How did the observers react to the photos? What was easy to explain, what was difficult? The teacher may ask students, what fascinated them most in the experiment on magic pictures. smartphone 10' 7) Optional conclusion As a conclusion, pictures by Fabian Oefner, photographer and artist, may be shown. The pictures may be seen at beamer, internet The teacher may show the students parallels between the process of creating the pictures and the creative process of technicians and artists: try optimize develop produce Fabian Oefner ( is a photographer. He developed the method for creating pictures presented here. Fabian Oefner has a lot to clean up every time he develops a new idea.

12 Accompanying units: 1) Magnetic flux lines The colored patterns of the magic pictures are not the magic flux lines. The following two methods illustrate, how magnetic flux lines can be made visible. a) Plate filled with liquid There are plates filled with liquid. The liquid contains iron filings. If you hold a magnet (red and blue) close to the plate, the iron filings arrange themselves according to the magnetic flux lines (see illustration below). Illustration 3: Iron filings in a plate filled with liquid can visualize magnetic flux lines. b) Glass plate on wooden cube A glass plate is placed on wooden cubes. Iron filings are placed on the glass plate. A green and red magnet is placed under the glass plate. The iron filings are distributed by slightly tapping on the glass plate with a finger. The way the iron filings arrange themselves shows the magnetic flux lines (see illustration below). Illustration 4: Iron filings on a glass plate make magnetic flux lines visible.

13 2) Use of ferrofluid Ferrofluid is used for e.g. high tech loudspeakers, diagnosis of cancer, cancer therapy and liquid (wear resistant) sealings. Findings on the magic pictures: Magnetism is an invisible force and can be made visible by means of magic pictures. By means of the experiment, insights into various areas can be gained: aesthetic (artistic perspective on magic pictures) technological (varying and improving the experiment) scientific (physical chemical background of the phenomenon of magic pictures ) Expert knowledge: See no. 4) Scientific explanation (spiky structure of ferrofluid, labyrinth effect) and accompanying units (magnetic flux lines, use of ferrofluid)