You will find that objects such as pictures and clip art are not always inserted onto a slide in the correct size. You can resize the object by performing these steps:
Select the object to resize. Selection handles appear.
Drag one of the following handles (the squares that surround the object) until the object is the desired size:
Drag a corner handle to change both the height and width of an object. PowerPoint retains the object's height-to-width ratio.
Drag a side, top, or bottom handle to change the height or width alone.
To keep the original center of the object stationary while sizing, hold down the Ctrl key while dragging a sizing handle.
Release the mouse button when you have completed resizing the object.