“Do you remember what your teacher taught you?”

Most of us don’t—those lecture notes, formulas, and slides blur with time. What we carry instead are the memories of people who taught—their kindness, their quirks, their humanity. This blog is my tribute,  my gratitude to all the teachers, mentors, colleagues and students who taught me and made me today what I am. I refer here to some of my related blogs that you may like to go through.

Professors who taught

I remember my IIT Bombay days. The precise fundamentals of structural mechanics may have faded from memory (as if I ever had!), but I still recall Prof. R. S. Ayyar from Civil Engineering at IIT Bombay. He taught us that engineering isn’t merely about steel and concrete—it’s about sincerity, commitment and integrity. His after-class conversations on responsibility and ethics have endured far in my life. And he shared his words of wisdom once again with me when I met him when I was  a Professor at Centre for Environmental Science and Engineering at IIT Bombay.

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Prof. R. S. Ayyar was Founding member of IIT Bombay’s Civil Engineering Department; served as Head of Department and later Dean (Planning). Alumni tributes remember him for “indefatigable energy” and love for structural engineering. His family endowed a chair and a conference room in his name at IIT Bombay’s Civil Engineering Department.

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Prof. D. B. Phatak—the open‑hearted Computer Science teacher—remains unforgettable. His belief in open knowledge, mentoring students freely, and embracing open-source philosophy—that’s the lesson that outlasts any line of software code. He was my tutor, and I fondly remember the assignment he gave us to write software code for the “knights tour”. When we struggled to write the code to ensure that the knight on the chessboard visited each square only once, without getting stuck, it taught me completely bizarre learnings in my life. It essentially said that when faced with a list of things to be completed, start with the less attractive options first, and save the best until the end. Thank you, Professor Phatak, for such a discovery. Read my blog ” The Game of Chess and the Knights Tour”.

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Prof. D. B. Phatak was at IIT Bombay since 1971; former HoD (CSE), first Dean of Resources (1995–98), founding head of KReSIT (1998–2002). Nationally recognized for work in large-scale digital education and technology initiatives; received India’s Padma Shri (2013). Associated with the Aakash low-cost tablet initiative and ranked among “50 most powerful people in India” (2009).

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Professors as colleagues

Professor Arvind Kudchadkar (APK) never taught me, but I was fortunate to work with him when I joined as a Professor at IIT Bombay. We resonated so well when it came to teaching and soon became close family friends. Prof. Kudchadkar was more than an academic leader—he was a mentor who shaped how young faculty should approach consulting while teaching. When he was Dean Research and Development, he mediated for me my first consulting project on optimum siting of ambient air monitors for Rashriya Chemicals & Fertilizers (RCF) in Chembur, Mumbai. “You must first learn to know your value” he said while fixing my fee to RCF (that was six times more than my humble estimate) and it was a lesson in self-respect, professional ethics, and confidence. Read my blog “Asking for the Right Fee” that describes APK

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Prof. Arvind P. Kudchadkar, Professor Emeritus Chemical Engineering; Dean R&D 1984–86 and then Deputy Director, IIT Bombay). Leader and institution-builder; after retiring from IITB, contributed to establishing DA-IICT.

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There are so many such Professors to remember during my undergraduate and post graduate days at IIT Bombay. The list is long, and I can go on and on.

At Asian Institute of Technology (AIT) in Bangkok, where I did my Doctor of Engineering. Two teachers redefined what it means to teach from the heart.

One such Professor was Fude. When I was about to get married as a student, I worried about the “cost of married living.” Sensing my stress, he called me to his room—that had his famous little bar where he would sip rum and coke after playing golf. After hearing me out, he offered me a job: “Wash my car every day, and I’ll pay you 500 baht a month.” The next day, he made sure the car was parked right by the main corridor, where everyone could see me. I felt embarrassed as students passed by with comments, while he sat on a stool, inspecting my work, giving me tips on washing—and importantly on life. When he handed me the money, he said, “Prasad—the idea was to teach you the dignity and pride of work, no matter what you do, and to make you humble.” Those words still stay with me. Read my blog Professor with Warm Eyes and Golden Hearts.

Prof. N. C. Thanh, though initially formal, revealed a deep, sentimental warmth. Once, he invited me and Dr. Bindu Lohani (my doctoral guide) for lunch at his home in Bangkok. He asked me to come early and took me to the local market, carefully choosing vegetables, meat, and fruit. “When it comes to friends, you must be involved from the beginning,” he said. The meal his sisters prepared for us was unforgettable. After lunch, while showing me his house, I admired his remarkable collection of handicrafts and antiques. As I was leaving, he handed me a large box. To my shock, it contained the very pieces I had praised. Embarrassed, I protested, but he smiled and said, “It is easy to buy gifts from a mall, but true giving is when you part with something of your own, with love and affection. My heart will be with you when you keep these artifacts in your house.” I still treasure those gifts—and his lesson on the art of giving. Do read my blog  “Professor Thanh teaches me the Emotional Art of Giving”

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Mentors who taught what was not taught in the classrooms

Many of us are fans of Dr. Deepak Kantawala, now 85 years old. He is to me a friend, philosopher and guide. We try to meet him with our group of “oldies” once a month for a breakfast. The conversations have always been enjoyable and give us an opportunity to continue to learn. Do read my blog “Keys to the Office of Dr Deepak Kantawala” .  In this blog I narrate a story how Dr Kantawala handed over keys to his office in full trust when we had other motive of photocopying some of his consultancy reports. We wanted to become consultants as good as him. But finally, we didn’t photocopy as ethics prevailed. When I confessed to him our intention, he smiled and said “I knew you and your friend were up to something – but what it was I wasn’t sure. He then patted on my back, and said “Prasad, if knowledge was so simple to acquire then universities and such halls of knowledge would have been long replaced by the photocopying machines!” I understood.

 

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Dr Deepak Kantawala is a well-known Industrial Wastewater / Environmental Consulting expert and Former Partner Environmental Engineering Consultants (EEC), Mumbai, earlier academic stint at MS University, Baroda. Served as Chairman, NEERI Research Council.

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Other example is Dr. Niloy Chaudhuri, Chairman of the Central Pollution Control Board. A patient listener and a thoughtful challenger – He encouraged ideas, even those ahead of their time, asking for space to think and adapt. Dr. Chaudhuri embodied empathetic leadership: authoritative yet humane. He trusted young professionals, offering consulting opportunities with remarkable freedom. After hearing me speak in Delhi at a conference, he noticed that I was shivering in the cold. So, he wrapped his coat around me, said to drop in next day and used it as an excuse to invite deeper conversation with him. Read my blog “Research interest and dividend in-practice -case of water quality-modeling

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Dr Niloy Chaudhuri was Professor of Civil Engineering, Jadavpur University; Chairman, Central Pollution Control Board (CPCB), Government of India (served 3 terms across ~15 years). As CPCB Chairman, Dr. Chaudhuri combined authority with empathy. With roots in academia and experience in policy, he bridged rigorous science with the demands of governance, shaping India’s environmental regulation in its formative years.

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Another person who influenced me was Prof. G. D. Agarwal (Swami Gyan Swaroop Sanand). In 1978, when exploring master’s options, I wrote him a postcard. He replied thoughtfully, comparing IIT Kanpur’s program to leading U.S. masters programs—instilling confidence in me. I met him in 1979 during a training program where I assisted him. His lectures emphasized practice over theory, and his conviction and clarity left a deep impression. He invited me to his farm in Kandhla, where he mentored me amid his books and stories of University of Berkeley. Later, I collaborated with him in Dhaka and professional forums—my relationship evolving from mentee to colleague. Read my blog “Remembering Guru Das Agarwal”

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Dr G D Agarwal was Professor and head Civil & Environmental Engineering at IIT Kanpur; Member-Secretary, CPCB; Honorary Professor, Mahatma Gandhi Chitrakoot Gramodaya Vishwavidyalaya. He led multiple hunger strikes to protect the Ganga, most notably in 2009 and 2018, bringing national attention to river ecology. He embodied integrity, and Gandhian simplicity. He was known as a teacher par excellence whose greatest lessons came from live examples. Left a legacy as both scholar and environmental crusader—combining science, ethics, and activism in a unique way.

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Professors with whom you circle back from Student days to become a Co-author

It is a great experience to get an opportunity to coauthor a book at a later date with the very author whose books you studied in the undergraduate days. These professors never taught me, but I learnt much more about their work and personalities while working with them on a book. I cite here examples of Professor Asit Biswas and Professor Emiritus Mac Berthouex.

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Prof. Asit K. Biswas, Founder, Third World Centre for Water Management; Distinguished Visiting Professor (Univ. of Glasgow) Globally regarded water expert; advisor to leaders in 20+ countries; co-founder of the International Water Resources Association and World Water Council. Stockholm Water Prize (2006)—for outstanding, multi-faceted contributions to global water issues. Founder/Editor-in-Chief, International Journal of Water Resources Development; author/editor of dozens of books and hundreds of papers. His book on Water Quality Management significantly influenced me in my career. Later I coauthored a book with him on Environmental Impact Assessment for Developing Countries that was translated in Chinese and Japanese.  I remember the long discussions I had in Quebec at the IAIA conference while developing this book.

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Prof. Paul Mac Berthouex, Civil & Environmental Engineering, University of Wisconsin–Madison (Emeritus Professor), Co-author of landmark texts including ‘Strategy of Pollution Control’ (1977, with Dale Rudd) and ‘Pollution Prevention and Control’ (2013, with Linfield C. Brown).  ‘Statistics for Environmental Engineers’ (1994). In 1984, while studying and teaching at IIT Bombay, I discovered his book ‘Strategy of Pollution Control’. Its systems-thinking approach helped me to integrate ecology, chemistry, microbiology, and separation techniques in an otherwise fragmented curriculum. When I started using this book as a textbook, Mac generously sent me the solutions manual then, an act of kindness that deeply supported my teaching. I later invited him in 1992 for a UNESCO-supported book project that we co-authored along with other experts. Read my blog on his two fascinating books.

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Teachers’ Day is also a day for teachers to remember their students.

Prof. Clement Prabhakar—once my student, now a professor at the University of Alabama—fills me with pride. He significantly contributed to the ground water model MODFLOW. I just spoke to him yesterday evening. It reminds me that teachers don’t just teach, they nurture future teachers, thinkers, and leaders. Clements passion for doing something useful for India, his love to teach and inspire students is just commendable. I have several other examples of my ex-students, all notable – like Professors Akhilendra Gupta at MNIT, Professor Arvind Nema at IIT Delhi, Professor Makarand Ghangrekar now Director – National Institute of Technology Puducherry, Professor Anju Singh at IIM Mumbai and Professor Upal Ghosh at University of Maryland.

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The Joy of teaching

Among all the roles I’ve worn—consultant, researcher, entrepreneur, writer—the one that brings me unwavering joy is being a teacher. Teaching isn’t just a job; it’s an ongoing dialogue with the future. It’s seeing curiosity light up in someone’s eyes, watching hesitant questions transform into bold insights.

Read my blog  “The Joy of Teaching”.  I say in this blog “I wish my last lecture is in a room with a blackboard with students sitting around me – eager to learn.  I will enjoy teaching them through “story telling” and it will be a great joy to see their faces getting slowly illuminated. This makes life worth living.”

Now here is my gentle, ungraded assignment on this Teachers’ Day:

1. Forget what you’ve forgotten.
2. Remember the teachers who go beyond the syllabus.
3. Honor those who became mentors, collaborators, or silent guides.
4. And if you teach—remember your students, for they are the living legacy of your teaching.

Because when lessons fade, it’s the teachers—(and the students they nurture)—that remain the living bookmarks of our lives.

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Sorry for this unusually long blog. I just thought of walking many of you down the memory lane. Hope you enjoy the stories. Do read my blogs cited in the text.