Rwanda is one of the smallest countries in Africa - about the size of Wales or the U.S. state of Maryland - but every part of it goes up and down. There is barely any flat ground. Farmers have learned to grow crops on the slopes by cutting flat 'steps' into the hillsides, called terraces. From the air, the whole country looks like green ribbons winding around the hills.
Most Rwandan villages and schools sit on top of a hill or along the side of one. To get from one village to the next, you often have to walk down into a valley and back up the next hill. Children get used to walking up and down hills every day - many say it makes them very fit by the time they are grown.
The hills rise gently in some places and steeply in others. The highest points in the country are old volcanoes in the north-west. The lowest points are river valleys in the south-east. In between is a great green carpet of crops: tea, coffee, bananas, beans and sweet potatoes, all growing on the slopes.
Mist often settles in the valleys early in the morning. From up on the hills it looks as if the country is floating on a sea of cloud. By mid-morning the sun usually burns the mist away and you can see for many kilometres - hill after hill after hill, all the way to the horizon.