Using the Flag to Work Straight Lines Learn how to use the flag to work straight lines to prepare for the show pen. By H&R Editors | August 23, 2021 | 1 minute read Click here to watch now! In this video, Winston explains why using the flag is beneficial for working straight lines. He explains that while working the flag, you’re in control and can control the tempo as your horse is learning. Click here to watch now! What did you think of this article? Submit Rating Thank you for your feedback!