My son started taking USACO classes with Dr. Zhu a few months ago after the pandemic started. He absolutely loved Dr. Zhu's classes. He is a kid who's hard to focus for a long time, but surprisingly, he was extremely involved and fully engaged for 2 and half hours whenever he takes Dr. Zhu's classes. He's made tremendous progress during the past few months. Dr. Zhu is knowledgable, experienced, detail oriented, and he has a great sense of responsibility toward helping his student improve. After each session, he sent out detailed and personalized emails to every parent to update their child's progress, next steps, and recommendations. From his emails, you can feel the passion and sense of responsibility. Both my son and I feel very fortunate to have such a wonderful teacher!