If it was previously used by a school district, I would think they probably wiped the hard disk and installed their own custom image (since they'd probably be replicating it over a whole stable of identical machines). If they did, there probably is no Recovery partition.
You're in a Win7 forum, so I'll assume the machine currently has Win7 on it. If it's Win7, you may be able to tell if there's also a Recovery partition if you can get a look at the partition layout. If you can boot to Windows, take a look in Disk Management. If you can't boot to Windows, try booting from a linux live CD and look at the partition layout of the hard disk. You can also use a bootable partition management CD like Mini-Tools Partition Wizard or Macrium Reflect, if you already have one of those.
If the hard disk has a factory recovery partition, Dell's standard practice was to install a tiny (40-90 MB) first partition for Dell Utilities, followed by a 10-15 GB Recovery partition, followed by one or two very large partitions encompassing the OS and the rest of the hard disk.
If it doesn't have that 10-15 GB Recovery partition, then you're out of luck. You'd have to start over with a clean install.