On this page of our guide to Psychonauts 2, we've listed the Nuggets of Wisdom available in Hollis' Classroom.
You can find three Nuggets of Wisdom in this level.
Nugget of Wisdom 1
To find this secret you need to jump across thoughts until you reach DISGUST, then jump down onto the platform below.
2nd Nugget of Wisdom
Location: Hospital Parking Lot.
The secret can be found in the bushes, in the hospital parking lot.
3rd Nugget of Wisdom
You'll found the final nugget in the chapel, right before the level ends.