left is primitive that tells a turtle to turn a certain number of degrees (between 0 and 360) to the left.

ask turtles [
    left 90
]

Things to keep in mind when using left:

• Turtle(s) will turn right if you provide a negative number.
• You can also provide a floating point number such as left 30.5 or left -185.3.

The model example below demonstrates how the left, and its sibling right, primitives work. We have 12 dots representing the 12 hours on the clock and an arrow representing the hour. When we click spin-left, our arrow turns left 1 degree at each tick until it completes the specified number of degrees on the slider.