Madonna started construction of her school for girls in Malawi last week by planting a tree at the planned site of the $15 million facility. The Queen of Pop, 51, arrived in the impoverished southern African country last weekend accompanied by her four children - daughters Lourdes and Mercy, and sons Rocco and David . Madonna adopted Mercy from Malawi earlier this year and adopted David from the country in 2008. Together with Lourdes she planted a Moringa tree, a hardy tree with edible leaves. “If this school is a success - with God willing it will be - we will replicate it not only in Malawi but in other parts of the world as well,” she said. The new school will be called the Raising Malawi Academy for Girls and will open by 2011 and educate 500 students. So take that, Oprah!