With annotations, you can add handwritten notes and drawings right onto your slides. Students will be able to see the annotations, but they can't draw on the slides themselves.

Click the 

icon to start or stop drawing mode.

You can choose what color to draw with by clicking the 

icon. With a mouse, draw by holding the left mouse button down and erase with the right mouse button. On a touchscreen, you can draw by touching the screen. To erase, touch and hold for half a second, then move to wipe away previous drawings.

Don't forget to save your annotations using the 

icon.