He won hearts with his portrayal of an engineering student in blockbuster 3 Idiots and Bollywood superstar Aamir Khan says the only reason he decided to act in the film was that its subject was education.

"I shouldn't have acted in 3 Idiots as in no way do I look like an 18 year old. The only reason I did the film was because it was about education," said Aamir.

The Rajkumar Hirani-directed film is the story of three students in an elite engineering institute reeling under pressure from the current educational system to excel in their career.

The 45-year-old actor has been passionate about the cause of education ever since he made Taare Zameen Par, the tale of a dyslexic child's struggle to cope with the existing norms of education.

"I was drawn towards stories about education ever since Taare Zameen Par and then 3 Idiots happened. Cinema has the ability to reach out to people and more films upholding this cause should be made," said the actor.

Besides education, Aamir is also associated with the cause of malnutrition. "All these issues are linked. I am working with the Women and Children Welfare ministry as well as the UNICEF for the betterment of malnourished kids."

The actor was in the capital today to launch the book Colours of my Rainbow by Himani Verma, which chronicles the charitable work of Salma Ansari, wife of the Vice President of India Hamid Ansari.

The book tells Salma's struggles to set up schools through her Al-Noor Charitable Society to provide education to marginalized and underprivileged children in Aligarh.

"It is very inspiring to see Mrs Ansari and her organisation trying to reach out to these children.

Contribution in the field of education is one of the most important things to do," said Aamir, who flew down from Germany where he was a jury member at the Berlin Film Festival.

Bollywood actress Gracy Singh, choreographer Shiamak Davar and designer Rohit Bal were also present at the launch.

