Amaryllis, Ginro and Kohaku are chosen to join the inner palace. The science team will need a way to communicate with them in secret, and, eventually, a way for them with the science team.
I think I did that in elementary school.
.أظنني قمت بذلك في الابتدائية
Das haben wir mal in
der Grundschule gemacht.
Lo hacíamos en primaria.
Lo hacíamos en primaria.
J’ai vu ça en primaire, il me semble.
Mi sembra di averlo studiato 
alle elementari o giù di lì.
Eu acho que fiz isso no primário.
Мы делали что-то такое
в начальных классах.