The fractional units of a ruler and measuring fractional lengths can be tricky, especially for students with processing, working memory, or visual related disabilities. For the students I have helped, here is the approach I have used.
I relate the fractional marks and counting them to walking across a set of stepping stones. This ties into their prior knowledge and allows for a hands on activity of moving the girl across the stones.
I present the girl and the stepping stones as the setting. Then I explain that she will take steps to walk across the stepping stones to the other side. Students count stones to determine steps. Below is an image of a Jamboard that allows for moving the girl.
Below is an image of a handout I use to address this prior knoweldge.