Are these brooder panels too short?

[brewfarm]

The height isn't the issue if you cover the top - chicks will fly out of anything that isn't covered. I brooded in a bathtub. A brooder can be as simple as some cardboard boxes taped together, but unless it's several feet tall it needs to be covered.

What you didn't mention was how many chicks you had in how much sq footage, nor why you think they need to be in a brooder for 10 weeks? If it's because of integration you'd be using some sort of pen or fenced off area by that point, not a brooder.

I don't think I need a brooder at 10 weeks. But, I think I need some kind of pen. Something where I can let chicks run around in the yard, play with hens, but have their own spot. The panels in my OP looked okay. It seemed like they would work and could be expanded, to make more of pen, as they got older.

Originally I had 50 chicks with 1/2 square foot per chick. I opened up the brooder at about 5 weeks. One side was covered with chicken wire so they could meet the hens, but were still in the brooder. I took down the chicken wire after about 2 weeks. So it was open on one side, still had the top I'd put on it, but did not have the heat lamps turned on. Everybody seemed to be getting along. After a week I took the brooder out entirely. The chicks decided to move to another corner and that's when things went south for me. Suddenly the chicks were piling at night- like they were cold or scared. It hadn't gotten colder. Then hens don't seem to care where the chicks are and I haven't seen any sign of predators. So I don't know what scared them.

I am thinking that I did it wrong and they should have still been separated, like in an x-pen that gave them 3/4-1 square foot each. I'm thinking that I should have gone brooder, pen, then coop. I don't think I integrated them or acclimate them to something well.

 

[SavKel&RynKel]

https://www.backyardchickens.com/articles/integrating-new-birds-at-4-weeks-old.72603/

Just food for thought.
In answer to your specific question, three week olds can jump 3 feet easy. So cover any "wall" if you want to kewp them in.

 

[FlyingNunFarm]

You may need to set them on a roost at night. If there is a low roost I’d use that. They still have the chick mentality of stick together and ball up. Once they sleep on a roost a couple of times they’ll get the idea.