We always started with the easy [words] I had already learned, and which I wrote down and read from the slate. The new ones I had to listen to first, putting them together as well as I could from the sounds. At the end of the lesson I had to listen to the formidable words that sounded more like trapezes in full swing. —Barrio Boy,
Ernesto Galarza

What does the simile at the end of the passage mean? Answer by completing the sentence.

Galarza compares the words to trapezes in full swing to explain that