World Thinking Day Ideas and Resources. Its aim is to bring together children from all over the world (nearly 150 countries take part) to celebrate international friendships, raise money and think about a global theme, which is changed each year. The theme for Thinking Day in 2018 is "Grow" - looking for "seeds of change" and planting a tree to make a difference. During the project the children will think about how they can be kind to each other and kind to the environment. Then on World Thinking Day we will all plant seeds somewhere in our schools and take photos to show that we are all working together to save the environment.