Wikipedia:Reference desk/Archives/Science/2014 October 20

= October 20 =

How text book problems are conceived
One question intrigues me and I do not find a satisfactory abswer .We all know that from   early school years textbooks exam suggestion books study material engineering entrance end semester exams we get increasingly challenging problems in Mathematics ,physics chemistry.The problems are based on the theory presented in the text and/or its extension and/or derivation.It can never be made out who when and how conceived such a magnificiently comPlex Problem.He has a advanced level of thinking comParable ti a scientist. Expecting answers from the learned community.As an example consider Schaum series Vector Analysis. If real life author share their views and discusses the topic then it will be great. — Preceding unsigned comment added by 117.248.139.68 (talk) 17:03, 20 October 2014 (UTC)


 * Amazingly, most text books explain this sort of detail in the preface. The author will usually break the fourth wall, so to speak, and address the reader to explain why the book was written, how the book was written, and for whom the book is intended.  The author will commonly explain the evolution of the book.  In the specific case you cited, Murray R. Spiegel was the author; he developed his excellent series of advanced mathematics books from the lecture notes he used when he taught undergraduate courses at RPI.  Nimur (talk) 18:56, 20 October 2014 (UTC)


 * A lot of school textbooks have teacher's editions] which may also help. (Go to their office hours, explain your curiosity and ask to look it over.) All's I can say is that when I tutor a student, I always work backwards from the answer. It's pretty much impossible to make complex, yet coherent questions otherwise.  For example, if I want a Spanish answer that has the Se lo... construction in it, I start with the answer "se lo" and add a verb and then ask a question "Cuándo le mostró el profesor el problema al estudiante?" that would elicit "Se lo mostró la semana pasada."   Same with math.  Start with 33 and ask what number divided by 7 equals 33.  If you start with, "What is 32/7 you are going to get monsters like 4.571428571428 and unless that's what you want (to demonstrate the repeating decimals of numbers divided by 7) it's a monster to deal with gradewise. μηδείς (talk) 22:29, 20 October 2014 (UTC)


 * My math teacher from last year went over this a bit during class one day. When writing a test she will start with the answer and work backwards.  It was a calculus class.  So she would just take the integral or differential of the answer to get to a problem for the test.  Dismas |(talk) 05:16, 21 October 2014 (UTC)


 * Occasionally I am a guest lecturer at a university and present a lecture to a class of twenty-year olds. I support my lecture with a couple of pages of type-written notes, ending with three exercises in the form of questions for the students to work through. The subject manager asked me to provide him with model answers to my three questions. I found it a useful and reinforcing activity to develop model answers. I think it would be a useful activity for teenagers studying math and science - as one optional exercise the teacher could ask for a question on the subject under study, and a model answer for the question. Marks awarded would be proportional to the degree of difficulty of the question, as well as to the correctness of the model answer. In this way, each student choosing the option would be grappling with a question of difficulty appropriate to their familiarity with the subject, and yet the question would not be intimidating because the students themselves have total control over the question. Dolphin  ( t ) 06:17, 21 October 2014 (UTC)

World record for widest monocrystalline silicon crystal
What's the current world record for the widest monocrystalline silicon crystal ever grown? WinterWall (talk) 21:17, 20 October 2014 (UTC)
 * Noone will do size world records with these. All production lines are build with unique machines that can only use the one size they are build for. See Wafer_(electronics). --Kharon (talk) 02:16, 22 October 2014 (UTC)
 * 450 mm ingots were being made more than five years ago. That's an aeon in the semiconductor industry. I was just wondering whether there's any improvements since then. WinterWall (talk) 12:45, 22 October 2014 (UTC)
 * 450mm hasn't taken off and I'm not sure now if it ever will. Dmcq (talk) 19:38, 22 October 2014 (UTC)
 * Yes, I agree. But my question is about the ingots and the ingots only. WinterWall (talk) 12:03, 23 October 2014 (UTC)