Demonstration in the classroom

o s t noteworthy is the stranee fact that we are the onlv school in our citv with an. ~ ~ r i c u l t u r e Department. The students in this departmen...
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Sidney P. Harris Chairman and Assistant Principal John Bowne High School Flushing. NY 11367

John Bowne High School is located in North Central Queens County, one of the five counties of New York City. Our school has a population of 3400, large by any standards. The abilities of the students generally conform to a bimodal distribution. Students in our elective courses eenerdv come from the upper 50% of the school population. ~ o snoteworthy t is the stranee fact that we are the onlv school in our citv with an ~ ~ r i c u l t u Department. re The students in this department comprise about 13%of the school population and come from four of the five counties in New York City. These students are largely above average in ability. In addition to their two periods of agriculture classes, these students are required to take a general academic course of study. These agricultural students also work on our miniature farm (now called a "land laboratory" hecause it occupies only four acres). Durine the summer. these aericulture students are usuallv employed on farms. These students make up a large proportion of the total enrollment in our chemistrv. vhvsics, and introductory physical science classes. In the special scienrei, we teach state mandated year-long courses. Thc chemistry course isa diluted formof the CHEM Study curriculum. We ha\,e six 40-min sessions per week to complete an overcrowded modern syllabus. Two connected periods are assigned to laboratory experiments each week. There is a similar course in physics. The average enrollment in these classes is 34 with the majority being in the 11th grade. Advanced nlacement classes are also offered in both chemistrv and physics. 'l'hew classes meet for seven periods per week and awruce about 2 1 studenw with 12th maders beine in the majority. i n applied chemistry and appiied physics~ourse, under the umbrella name "Applied Science" is also offered for the non-college hound student. Our program includes a total of ten chemistry classes.

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My Philosophy

In the classroom, I believe there is no substitute for enthusiasm for the subject. Of course, this alone is not sufficient. The teacher must also encourage students to participate and Sidney Harris received his BS in Chemistry in 1937 and his MS in Chemistry and Education in 1940 from The City College of New York. In 1965, he received his MS in Chemistry from Adelphi University. He hss been teaching for 32 years and is currently the Chairman and Assistant Principal of the Physical Science Department at the John Bowne High School. Mr. Harris is a highly respected memher of our profession. His interest and dedication to chemical education has been recognized by a number of awards ineludina: 1961,Award of The Chemists' Club; 1974,Nichols Award of the New York ACS Section; 1975,Manufacturing Chemists' Eastern Regional Award; the 1977 Foster Award in Chemistry; and the 1977 James B. Conant National ACS Award. He is a memher of the ACS and has been very active in his local section. He is also a memher of the ACS Speakers Tour (Prospective Speakers List) which aims t o motivate students toward scientificcareers and science research.

take an active role in the learning process. I believe in teaching a complete course with attention to details, hut in turn, I attemnt to nresent these details in an interesting" and relevant . fashion. There are manv reasons for usine demonstrations in the teaching of chemistry. The old adage "seeing is believing" holds true here. Demonstrations usuallv increase student interest, thus Iuse them tomotivate discukion about the topic being studied. Many students are not in the habit of asking questions. Demonstrations provide a useful vehicle in changing student attitudes in this respect ( 1 1. Demonstrations may even be used to summarize or review various aspects of chemistry. Demonstrations may supply the concrete evidence for students who have not reached the level of concept formalism (2).Opportunities may also arise to investigate reasons for the failure of some experiments (3).

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Stoichiometrlc Demonstration The mathematics of stoichiometry sometimes overshadows the experimental basis of the topic. I have found that if I summarize the topic with the following demonstration, the students have an easier time comprehending and applying what they have learned. 2 MnOl-(aq)

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+ 16 Hc(aq)+ 5 C10n2-(aq) 10 COdg)

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2 Mn2+(aq) 8 H20(1)

As a part of the demonstration, we carry out the weightweieht (actuallv mass-mass) determination assuming we beein witk 0.0100 mole of KMn04 (1.55g). The studen