How we cite our quotes: (Chapter.Paragraph)
Quote #10
"This morning," Matilda said, "just for fun I tried to push something over with my eyes and I couldn't do it. Nothing moved. I didn't even feel the hotness building up behind my eyeballs. The power had gone. I think I've lost it completely." (21.15)
When Matilda tries "just for fun," she's not able to use telekinesis any more. Not even a little bit. It's like she never had the power in the first place. It has vanished into thin air. After this, Miss Honey suggests that Matilda lost the power because it was based on her extra brain juice; she had extra mental energy to burn and it was shooting out like telekinesis. But once she moves up to a challenging class, the extra energy gets used up.
You could also say, though, that when Matilda uses her powers earlier in the book, she's either really mad about unfair treatment or trying to prevent unfairness. And once the Trunchbull has been stopped, a lot of that unfairness goes away. Now she has no justice to dole out, so her powers are unnecessary.