Australian supermodel has been chosen again to be Earth Hour ambassador. This year, Miranda is willing to conduct a free yoga class as part of her "I Will If You Will" challenge.

Miranda Kerr is pleased to announce that she will be again a part of Earth Hour's meaningful project of saving the environment. Miranda happily announced this exciting news via her Twitter and Facebook accounts.

According to Miranda, she will conduct a free public yoga class if 500 people will upload their own version of IWIYW challenge. People can attend Miranda's free yoga class by taking the IWIYW challenge and get a chance of winning tickets for two.

The yoga class will be held in Sydney. Winners will take home tickets for the class and KORA Organics gift pack. Miranda Kerr urged her family, friends and business partners to participate in the cause.

According to the Australian beauty, "Earth Hour is (all) about encouraging positive action and that is exactly why I have chosen to be involved. I believe we can all do our best to make small changes to create positive effects."

Last year, Miranda was also named as ambassador for the event providing tips on how to help in saving the environment through simple ways.

Earth Hour is an annual global event organized by the World Wide Fund that is held every last Saturday of March. Every year, the organization asked every household to participate by turning off their lights for an hour in order to raise awareness about the need to conduct immediate action against climate change.

Sydney, Australia pioneered the Earth Hour in 2007 as organized by WWF and Sydney Morning Herald in 2007. That year, 2.2 million Sydney residents participated by turning off all of their non-essential lights. Following Sydney's lead, other cities adopted the concept in 2008.

Miranda Kerr closed her post with a firm statement and a reminder for all, "I urge us all to be involved and join in the conversation and of course don't forget to turn the lights out at 8.30pm [on] March 31st 2012."

Watch the video of Miranda's IWIYW challenge and accept if you dare.

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