If you have a garden, put out plenty of large toys, such as a swing, climbing frame or mini-roundabout.
Even if you don’t have a garden, give her a pedal tricycle or a pull-along toy that she can play with in the park. This gets her used to being outside the house.
And she’ll soon start to notice what goes on around her. (Diggersite at Yishun is a fun alternative, too.)