This is level 13 of the B-Tunnel.
Unlike the previous few levels, this one is quite easy. You just need to locate the crumbling tiles and step on them. You can also step on the thick heptagonal rings.
After this level, a cutscene is activated.
After this level, the Child asks the Student about her lab coat in level Level B-12. She says that there is no dress code for science as it is the form of forming hypotheses and disproving them. The Child gets bored. So the Student says that not all school science is boring. The Child says that he doesn't need science. The Student mumbles 'Oh, so that's why...' and says 'Let me get back to you on this.' More can be seen on the Story page.