In this task, you're given passages that contain mentions of names of people, places, or things. Some of these mentions refer to the same person, place, or thing. Your job is to write questions that evaluate one's understanding of such references. Good questions are expected to link pronouns (she, her, him, his, their, etc.) or other mentions to people, places, or things to which they may refer. Do not ask questions that can be answered correctly without understanding the paragraph or having multiple answers. Avoid questions that do not link phrases referring to the same entity. For each of your questions, the answer should be one or more phrases in the paragraph, and it should be unambiguous.

Passage: After their HIV positive mother's death, Derick and Margaret collect wood and construct a human-length box with wheels. Then, they journey with it from Kampala to Kasangombe in a heartbreaking bid to overcome poverty and experience hope. The journey throws them dangerous experiences on unpredictable Ugandan roads. Their mother's dying wish had set them off on a seemingly impossible journey to find a relative they do not even know.
Before her death, she leaves them an envelope addressed to her sister (their auntie) who is married to a hard-working man living in a distant village called Kasangombe with their kids. Ingeniously, Derick creates a coffin using wood he collected from a rubbish dump and adds luggage bag rollers brought by Margaret. On their journey from Kampala City to their aunt's place, they are offered a lift by a seemingly kind man (played by Joel Okuyo Atiku) in a truck who is amazed by their "box". He introduces them to a kid he had taken under his wings relaxing at the back and shows them a photo of a house they can possess if they work for him. At night though, Margaret sees a scary dream where their helper is not exactly as kind as he seemed so she runs out of the truck. Derick follows and the boy throws out their coffin before waving. They walk the rest of the distance.
Initially, their uncle (played by Isaac Muwawu) did not want them in his house because he thought they were HIV-infected. Derick overheard him quarrel with his aunt at night and shook Margaret in the morning from another dream (this time beautiful, where both siblings were smiling and enjoying a picnic in a glorious garden with their aunt, uncle, cousins, dead parents and some whites). Derick convinced her to walk away from the home with him but without a reason.
What's another word for the human-length box with wheels that the siblings construct?