What was miss kinnian upset about in April 15 in flower for algernon?

In "Flowers for Algernon," Miss Kinnian is upset on April 15 because she feels a sense of loss and concern for Charlie Gordon, who has undergone experimental surgery to increase his intelligence. As Charlie's cognitive abilities grow, he begins to change in ways that alienate him from those around him, including Miss Kinnian, who cares for him deeply. She worries about the emotional and psychological toll the changes will have on him, especially as he starts to understand more about the world and his own limitations.