https://www.cnet.com/news/stranger-things-star-hopper-denies-eleven-has-powers-david-harbour/

In a video released by Netflix on Tuesday, the Stranger Things star admits that once his character began to treat Eleven as a daughter, he just couldn't be up-front about her abilities.

"I don't think he can actually view her powers in the same way that other people view her powers," Harbour said. "Because Hopper is looking at her to be a little girl that he can care for. So when she throws the book with her mind, or when she breaks windows, he can't take that in, because it would be too terrifying."