The well known Australian science communicator and populariser did just that with 600 or so students from Smiths Hill High School last Friday.

But speaking to the Mercury after the Science Week talk, Dr Karl bemoaned the lack of government investment in education.

"This is a wonderful school but every school should be like this," he said.

"I had 28 years of education for free including 16 years at university for free because back then the Australian governments, state and federal saw education as a worthwhile investment in the future.

"Somehow we don't do that anymore and I think that is a really big mistake that is going to cost the country so much more...firstly in terms of extra jail costs, social welfare and unhappiness and secondly in loss of potential income.

"The state glorifies in the educated citizen. It can only make things better."

The 71-year-old radio and TV presenter, who went to Edmund Rice College and the University of Wollongong, said he jumped at the chance to speak at Smiths Hill.

"The average person I'm trying to speak to is a 10-year-old with a sense of curiosity," Dr Karl said.

"There is no assumed knowledge. They don't have to know anything about metallurgy or quantum physics or aerodynamics but I'll try and take them on a little ride where they can learn amazing things in each of those fields and come away feeling really good."

Smiths Hill year 11 students Benjamin Yan and Nina Lawson were suitably impressed.

"It was really inspiring. I love science to begin with but that just gives me the motivation like to really put a lot of effort into it," NIna said.

"I've heard him on the radio a couple of times and I really enjoyed listening to that and this was 10 times better."

Benjamin added Dr Karl was really engaging.

"He was really interesting but more importantly he gets you engaged so you want to know what he is talking about rather than just presenting you some random facts," he said.

Dr Karl moved from Sweden to a migrant camp in Victoria, Australia with his Polish-born parents when he was just two-years-old, before settling in Wollongong three years later.

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He said he jumped at the chance to talk at Smiths Hill when asked by a parent at the school.

"Absolutely honoured to have the opportunity to talk to them. I was very thrilled," Dr Karl said.

"I was trying to give them an overview, firstly of future careers in science and not in science.

"Secondly to give them a balanced view of the world and thirdly through messages of hope that we can fix global warming, that they are smarter than their parents and that we are living in the most peaceful time of the history of the human race."