One that I used in my Test Community of Practice was https://www.tomwujec.com/design-projects/marshmallow-challenge/
It gets them used to working to a timescale, using limited resources, and when it is all done you can find out how it went.
Did they go all in trying to build the biggest thing they could, not giving themselves time to make sure it worked? Did they test their design?
How experienced is the test team? Are they new to testing and you are trying to teach them the basics and build up from there? Are they seasoned and you want to help improve any gaps they have but overall they are good testers? As depending on where they are and what they can do, group sessions testing some of the sites listed on Products and sites to practice testing on might be worth it too.
I gave an overview of Pair Testing and Exploratory Testing by getting them to test a dummy site riddled with bugs, and got them to test in different ways, communicate, maybe give them hints to different things they could look for.