A few weeks back, as part of my work, I had to develop some formative assessment questions with solutions, to go with elearning modules related to Standard 12 physics curriculum prescribed by the Central Board of Secondary Education, New Delhi.
As textbooks related to this curriculum are published by another central government agnecy known as National Council of Educational Research and Training, and as most CBSE affiliated K-12 schools use these books, I had to read the NCERT physics textbooks for grade 12, in order to gain an understanding of the pedagogical objectives (of NCERT) in designing these questions.
Let me present an excerpt from the NCERT textbook for Standard 12. This is an end of a section question.
"In the Rutherford’s nuclear model of the atom, the nucleus (radius about 10¯¹⁵ m) is analogous to the sun about which the electron move in orbit (radius ≈ 10¯¹0 m) like the earth orbits around the sun. If the dimensions of the solar system had the same proportions as those of the atom, would the earth be closer to or farther away from the sun than actually it is? The radius of earth’s orbit is about 1.5 X 10¹¹ m. The radius of sun is taken as 7 X 10⁸ m".
(Source: NCERT PHYSICS TEXTBOOK for Class XII Chapter 12 ATOMS p418cf)
We can easily see the oddities in the question. If I were to write the question, my version would be as follows:
"According to Rutherford’s model of the atom, electrons orbit round the nucleus like planets revolve round the Sun. Assuming the dimensions of the atom and that of the solar system (as given in the data below) to be of the same proportion (which in reality, is not), state how the Earth would be positioned from the Sun.
Data: Actual radius of orbit of the Earth is about 1.5 X 10¹¹ m".
However, at the K-10 level, I have found NCERT textbooks to be better than those published by many private publishers.
In 1985, when I was teaching physics at Cochin Refineries School in Kerala, India, we were using NCERT textbooks. [This was one of the best schools where I worked: well disciplined students, friendly colleages in a cordial and hospitable community]. At that time, I wrote to NCERT by pointing out mistakes in their textbooks and suggesting corrections. Probably my suggestions were considered. I found their later editions to be free from mistakes.
Contents in science textbooks should be presented in unambiguous and simple language without unnecessarily long words, phrases and sentences (for example `two minutes' would be better then `a couple of minutes'). This will enable students to understand concepts better.
Instead of being a database of how much or how best we know about lesson concepts, textbooks should pave the way for children's curiosity and help them to spread their wings so that they can begin to explore concepts from their points of view. Besides, textbooks should be accompanied by teachers' guides which offer guidance to teachers in a systematic manner based on research evidence of good practices.
Instead of being a database of how much or how best we know about lesson concepts, textbooks should pave the way for children's curiosity and help them to spread their wings so that they can begin to explore concepts from their points of view. Besides, textbooks should be accompanied by teachers' guides which offer guidance to teachers in a systematic manner based on research evidence of good practices.
