They lost their home in Manchester when Sarah's partner threw them out, and had to live in bed-and-breakfast accommodation for three weeks before being moved to the hostel by Shelter, creating huge problems for Jenny.
"School starts at 8.10am so I had to leave at 7am, often without breakfast, as there were strict rules about mealtimes," Jenny explained.
Doing homework was almost impossible as the hostel would not allow Jenny into their room on her own, and her mother did not return from her job until 9.30pm. So Jenny often got detention for not submitting homework.
And the stigma of homelessness meant that she was bullied.
"In French, the teacher would say, 'Describe your home,' and I just didn't want to," Jenny said. "I was too ashamed to say anything, and then the others would go on at me."
Inevitably, her grades dropped and she often found it difficult to go into school, which consequently wrote to Sarah expressing concern about Jenny's poor attendance.
"In the end, Shelter wrote them a letter explaining the situation," Sarah said. "I really feel we could have done with a bit of understanding rather than criticism."
After eight months, Jenny and her mother got a flat much closer to school.
Jenny plans to retake her GCSEs at college next year, and has won an award for good school attendance.
They would both like to see greater understanding. "It's not just people sleeping on the street who are homeless," said Sarah. "It could happen to anyone."
Names have been changed