The scale-like thing is the Zoom Slider.

• By clicking the '+' or the '-' button on the top and bottom of the slider, you can zoom the map in and out.
• By clicking and holding the centre circle button and dragging it up and down the scale, you can zoom the map in and out.
• By clicking and holding the centre button and dragging it up and down the scale, you can zoom the map in and out.