The Post Office - Korczak wanted his children to learn how to welcome the Angel of Death in the Warsaw Ghetto.

I do not know how the scene looked like at 16 Sienna street in Warszawa Ghetto. May be like on the picture above?

SWEDISH MOVIE In 2015 a group of puppeteers, actors and artists led by Silvia Bergman envisioned The Post Office play by Rabindranath Tagore as a puppet movie. The original movie was in Swedish.

The children at Korczak´s Orphanage Dom Sierot had a special group that performed plays. The last play that was performed was The Post Office by the Bengali playwright (Nobel prize winner) Rabindranath Tagore. The play was staged in the orphanage by the theater class of 1942 and the last performance took place just days before the Big deportation took place in the Warszawa ghetto. On the 15th of July 1942, Korczak sent out invitations for the performance. The Post Office is a play in two acts. Its story is about a young Indian boy called Amal whose role was played by a child called Abrasha and whose performance left everyone impressed.

Amal had a terminal illness. The Post office opened next to his house and Amal waits in his bed for a letter from the king wishing he will fall asleep forever with a smile.
The children in the orphanage identified themselves with Amal and with bated breath,  they awaited, together with Amal for the king’s letter that would spell redemption.

Amal stands in Madhav's courtyard and talks to passers-by, and asks in particular about the places they go. The construction of a new post office nearby prompts the imaginative Amal to fantasize about receiving a letter from the King or being his postman. The village headman mocks Amal, and pretends the illiterate child has received a letter from the king promising that his royal physician will come to attend him. The physician really does come, with a herald to announce the imminent arrival of the king; Amal, however, dies as Sudha comes to bring him flowers. Korczak wanted his children to learn how to welcome the Angel of Death calmly and this was his way of conveying this message.

Amal stands in Madhav's courtyard and talks to passers-by, and asks in particular about the places they go. The construction of a new post office nearby prompts the imaginative Amal to fantasize about receiving a letter from the King or being his postman. The village headman mocks Amal and pretends the illiterate child has received a letter from the king promising that his royal physician will come to attend him. The physician really does come, with a herald to announce the imminent arrival of the king; Amal, however, dies as Sudha comes to bring him flowers.

One of the 17 documents connected to Janusz Korczak/Henryk Goldszmit from Ringelblum Archive is the famous invitation to the "last play in Warszawas Ghetto. At this address, "Kitchen" the secret kibbutz of Chaluc organization was housed. It was run a.o. by Zivia (Cywia) Lubetkin and Yitzhak (Ichak) Cukierman. There was a regular lecture program run at 34 Dzielna Street almost every day. Janusz Korczak had a lecture at the kibbutz on January 18, 1942 and Stefa Wilczyńska on January 20, 1942.
This special invitation was written by Stefa Wilczyńska and sent by the messenger to three persons at Dzielna. It is not known who was the third person on this invitation - P. (Pani - Mrs) Sara. 34 is the number of Dzielna Street and 8 is the flat number where Lubetkin and Cukierman lived.

What is written on another side of this famous invitation? (top picture)
There are three names there...P. Cywia... P. Ichak... and P. Sara
P. Cywia = Pani Cywia Lubetkin.
P. Ichak = Pan Icchak Cukierman.
P. Sara = ?