- lesson-1 -> lesson-1-1-intro
- lesson-1-1-lines -> lesson-1-4
- lesson-1-4 -> lesson-1-body-fa
- lesson-1-buying- -> lesson-1-i-am-a-
- lesson-1-i-am-a- -> lesson-1-now
- lesson-1-number- -> lesson-1-the-str
- lesson-1-the-sun -> lesson-10-1
- lesson-10-1 -> lesson-10-electr
- lesson-10-enzyme -> lesson-100b-isai
- lesson-100c-isai -> lesson-11-2
- lesson-11-2 -> lesson-11-relati
- lesson-11-remote -> lesson-12-1
- lesson-12-1 -> lesson-12-monast
- lesson-12-monast -> lesson-13
- lesson-13 -> lesson-13-genesi
- lesson-13-graphi -> lesson-14
- lesson-14 -> lesson-14-power-
- lesson-14-quiz -> lesson-15-3-exch
- lesson-15-4 -> lesson-16
- lesson-16 -> lesson-17
- lesson-17 -> lesson-17-the-pa
- lesson-17-theme- -> lesson-19
- lesson-19 -> lesson-1c-how-yo
- lesson-2 -> lesson-2
- lesson-2 -> lesson-2-2-betwe
- lesson-2-2-condi -> lesson-2-6-direc
- lesson-2-6-examp -> lesson-2-democra
- lesson-2-designi -> lesson-2-install