What does Ender mean when he says he wants to keep practicing with the Launchies because “From you, I can learn what nobody knows”?

Ender's statement "From you, I can learn what nobody knows" in "Ender's Game" implies that he believes that practicing with the new Launchies can teach him new things that he cannot learn from practicing with his experienced friends. He values practicing with novices because they have not yet developed ingrained tactics and can approach challenges with a fresh perspective.

In the novel, Ender is being moved up to a new group of Launchies who are new to the Battle School. His desire to practice with them comes from his observation that they have not developed the same tactics and strategies as the more experienced students. He sees this as an opportunity to learn new ways to approach challenges. He also feels that he can help the Launchies improve by teaching them the tactics he has learned from his more experienced friends.

This statement shows that Ender is constantly looking for ways to improve and learn, even if it means seeking out new challenges and working with those who are less experienced. He understands the value of diversity and different perspectives and is willing to push himself to learn from others.

As Ender says later in the book, "The best way to learn is by doing. The only way to build a new tactic is to try it out in battle, see if it works, and improve it until it is as good as you can make it." Ender's desire to practice with the Launchies is an embodiment of this philosophy, as he seeks to learn and improve by trying out new tactics and approaches.