The number of homeless students in the US is the highest in more than a decade according to a new study.
Most of the 1.5m homeless children stayed with other families or friends after losing their homes.
But 7% lived in abandoned buildings or cars, the report by the National Centre for Homeless Education showed.
Homelessness is often caused by job insecurity, unaffordable housing, domestic violence and recently the opioid crisis.
Living without a fixed address has a serious impact on children's education and health.
Less than a third of homeless students were able to read adequately, and they scored even lower in mathematics and science, the report showed.
"Homeless children are in crisis mode, and because they don't have the luxury of focusing on school, they often fall behind," Amanda Clifford, of the National Youth Forum on Homelessness (NYFH), told the BBC.
The most recent data was recorded in 2017-18 and was more than double the nearly 680,000 homeless students reported in 2004-05, the director of National Centre for Homeless Education told the New York Times.
The research measures the number of children in schools who report being homeless at some point during an academic year. As such, it does not show the total population of homeless young people in the US.
Why is student homelessness increasing?
Homelessness is a growing problem in the US, usually linked to the national housing crisis.
Millions of people spend more than half their income on housing, and many report they cannot afford to buy a house.
Increasing rents and a housing shortage has forced thousands of people in California to live in caravans or inadequate housing.
A changing economy, with factories closing down or the rise of the insecure gig economy, also leaves parents unable to pay rent.
The opioid crisis, in which almost two million people are addicted to prescription drugs, is also causing some families to break up or children to be removed from their homes.
A disproportionate number of homeless youth are LGBT, according to University of California Williams Institute.
Nearly seven in 10 said that family rejection was a major cause of becoming homeless, and abuse at home was another major reason.
What are the solutions?
Most experts say the solution lies in providing more housing at affordable rates, as well as providing support to families who may be affected by trauma or addiction.
"Addressing the immediate needs of families is important - providing housing and the next month's rent. But beyond that, people need to be supported after their crisis has ended," Ms Clifford, of the NYFH, said.
For example, that could include paying for car repairs, so a parent can ensure they can travel to work.
Tracking how children are performing at school over a longer period of time is also important, Ms Clifford says, because the impact of homelessness can continue even if a child is in stable housing again.