IN THE CLASSROOM
How to film locomotor skills.
Skill Grader can only measure what it can see. A few simple habits on the oval make the difference between a clean result and a reshoot.
Timothy Starkey
PE teacher and founder of Huddl · 4 min read · October 2026
When a Skill Grader result looks off, the cause usually has nothing to do with the student. It comes down to where the camera was. Film from the wrong angle, or let a student run out of frame, and even the best algorithm ends up guessing.
The good news is that filming well is easy once you know why the rules exist. Here's what matters, and why.
Why side-on matters
Skill Grader uses pose estimation to find the body in each frame of video and follow the joints as the student moves. From those joint positions it works out angles and distances, like how high the knee lifts or how far the body leans forward.
A video is a flat, two-dimensional picture of a three-dimensional movement. Anything that happens across the camera's view is measured accurately. Anything that happens towards or away from the camera gets squashed. Locomotor skills like running, galloping, hopping, skipping and leaping all travel forward, and most of the important action happens in that forward and backward plane, which biomechanists call the sagittal plane. Film from the side and you're looking straight at it.
Film from the front and the same movement gets flattened. A knee driving up towards the camera looks almost straight, the stride shrinks to nothing and the forward lean disappears. That's why every locomotor skill in Skill Grader is filmed side-on.
Same skill, two angles. From the side, every joint angle Skill Grader measures is in view. From the front, most of them are hidden.
Setting up for running
Every skill has its own setup, and Skill Grader shows it on screen before you start filming. For running, set up two cones 10 metres apart and stand side-on, 3 metres back from the running path. The student runs to the far cone and back past the first, and you track them with the iPad as they go.
The Before you film screen. It appears at the start of each running assessment, so the setup is always the same.
Three metres back is close enough to see each joint clearly and far enough to keep the whole body in view. I'd also recommend setting up away from the rest of the class, so you're not filming other students in the background.
Five habits that make a difference
What happens to the video
Once the grade is worked out, the video is deleted. Skill Grader only keeps the measurements and the grade, so no footage of students is ever stored or shared. It's worth telling students that too, because it takes a lot of the pressure off being filmed.
What's coming next
Running is available now, galloping is in testing, and hopping, skipping and leaping are on the way. Each one will come with its own setup guide in the Skill library, but the side-on rule stays the same for every locomotor skill.
A minute spent setting up properly saves a lot of reshoots. Get the angle right and Skill Grader will do the rest.
Keep reading.
IN THE CLASSROOM
6 min
Understanding the running skill
Seven things, seven cues.
THE SCIENCE
5 min
The science of cadence
Quick, light steps.
PRODUCT UPDATE
5 min
Introducing Adapt
Fair results for every student.