You can’t teach sports unless you have a gym. And it’s the same idea for the 21st-century skills we want to teach kids: innovation, creativity, critical thinking, deep understanding of science and technology. If you don’t have a place to teach these skills, you can’t really do a good job.
You can’t teach those skills in a classroom with 40 chairs and a blackboard. That’s just not how scientists work; that’s not how technologists work. It’s not a good way to teach those skills.
In the same way that we can’t assess these skills with a traditional paper and pencil test, you can’t test if someone can swim well by giving them a multiple choice test.