Acer has announced two new Chromebooks specifically designed with the classroom in mind. The C910 is a 15 inch Chromebook and the C740 is a 11.6-inch Chromebook. Both have durable shells and reinforced hinges and can withstand up to 130 pounds of force and an 18" drop.
Both can be configured with 2 or 4 GB of RAM. The C740 starts at $259 and the C910 starts at $299 and has options for 16 or 32GB SSD and 1366 x 768 or full-HD screen. Battery life is 8-9 hours and you can get either an Intel Broadwell Core i3-5005U or Celeron 3205U. Having used an i3 Chroembook and Chromebox, I highly recommend getting this option for exceptional performance.
Both go on sale in February.
We have thousands of the C720 Chromebooks and the work great and hold up well, but these two new ones are even better.
Google for Education Resources (includes Chromebook resources)