EXHIBIT 10.11
LEASE COMMENCEMENT AGREEMENT
     Pursuant to the 5th Amendment to the Lease dated the 31st day of August
2005, entered into by and between 1899 L Street Tower LLC, as Landlord, and
Blackboard, Inc., as Tenant.
     Landlord and Tenant do hereby agree that the tenant previously occupying
the “Additional Third Floor Premises” vacated as of December 16, 2005. Per the
5th Amendment to the Lease dated the 31st day of August 2005, the lease
commencement date of the “Additional Third Floor Premises” shall be the date
that is fifteen (15) days after the tenant previously occupying the “Additional
Third Floor Premises” vacates. Therefore, Landlord and Tenant do hereby declare
that The Lease for the “Additional Third Floor Premises” is in full force and
effect and commences as of the 1st day of January, 2006; Landlord has fulfilled
all of its obligations under the Lease required to be fulfilled by Landlord on
or prior to such date; and Tenant has no right or set-off against any rentals.
The Rent Commencement Date is hereby established to be January 1, 2006.

                                  WITNESS:   LANDLORD:             1899 L Street
Tower LLC
 
                                By   /s/ Mellonie Sanborn   By   /s/ John F.
Loehr                                      
 
                               
Name:
      Mellonie Sanborn   Name:       John F. Loehr            
 
                               
 
                                WITNESS:   TENANT:             Blackboard, Inc.
 
                                By   /s/ Chelisse Dunn   By   /s/ Matthew Small
                                     
 
                               
Name:
      Chelisse Dunn   Name:       Matthew Small