Literally forces them? probably No. Compels them by threats of expulsion from school, lower grades or stigmatisation - Probably Yes.
Each September the cotton harvest begins. Many rural schools are closed down by government officials as children, some as young as nine, are forced to pick cotton by hand for up to three months in order to fill the shortfall in voluntary adult labour. They receive little, if any, pay.
And it's not just limited to children
Forced labour within the industry does not just affect children. Local administration employees, teachers, factory workers and doctors are commonly forced to leave their jobs for weeks at a time and pick cotton with no additional compensation. In some instances refusal to co-operate can lead to dismissal from work.
source
Additionally, there was a BBC Newsnight report on this subject back in 2007
As part of a special report we filmed children in Uzbekistan being forced to work in cotton fields instead of going to school.
However, the Uzbek embassy denied even then that they use Slavery, torture or coersion
The legislation of the Republic of Uzbekistan forbids any form of child labour on the cotton fields. full statement
Have things changed since 2007? Probably not, the BBC again ran a piece in September of 2011 which reports the situation to be mostly the same.
The BBC's Uzbek service has received reports of school children being
bussed to agricultural areas in various parts of the country.
One human rights worker in Uzbekistan said she had talked to a
10-year-old girl who said her class was made to pick cotton in the
mornings and attend lessons only in the afternoon.