In honor of the Best School Day campaign – which was inspired by all the work Stephen Colbert has done for South Carolina schools – the Late Show host recently returned to his elementary school in Charleston to catch up with his all-time favorite teacher from fourth grade for their first chat together in 40 years. Ms. Katsos is clearly very proud of her former student and even saved a cassette tape from 1974 where the little Colbert managed to ace a test while keeping her laughing the whole time. Be warned that if you are a sentimental person, this clip might cause you to feel lots of strong, heartwarming emotions.