Thematic units are a great way to think about PBL. Every project should have a theme to focus the content and learning. For example, I have centered projects around solar power, wilderness survival skills, and the nature of reality. Before I dove into the deep end of PBL, I crafted thematic units. In fact, my first attempt at PBL, back in 2014, was a glorified thematic unit about bullying and school violence.
As the anchor text, I showed the documentary Bully. I think nowadays they are calling it The Bully Project. They have a lot of resources on their site, and my students really responded to the film.
I don't know if you've ever heard the song "The Last Stand of Shazeb Andleeb." It's a Frank Black song about a kid named Shazeb Andleeb who was beaten to death at school in Los Angeles. I used the song in my unit, and we analyzed the lyrics.
We also read an article about the incident: https://www.latimes.com/archives/la-xpm-1995-05-19-me-3412-story.html
My students made an anti-bullying campaign in which they created flyers to promote Blue Shirt Day, made a bulletin board for the school, and wrote a research paper about how bullying impacts public health. (Here’s the scaffold I used to help my students write the paper.)
This is not a great example of project-based learning, but it is a good example of a thematic unit. More importantly, it gave me a place to build from. If you want to use PBL, there’s no easy way to do it. Start with a thematic unit and build from there.