**EXHIBIT 10.12****SIXTH AMENDMENT TO LEASE AGREEMENT**     **THIS SIXTH AMENDMENT TO LEASE AGREEMENT**(this “**Amendment**”) is made as of the 27th day ofJanuary, 2006, by and between **1899 L STREET TOWER LLC**, a Delaware limited liability company(“**Landlord**”), and **BLACKBOARD INC.**(“**Tenant**”).**W I T N E S S E T H**:     **WHEREAS**, 1899 L Street LLC (“**Original Landlord**”) and Tenant entered into that certain OfficeLease dated November 22, 1999 (the “**Original Lease**”), as amended by that certain Amendment to LeaseAgreement dated February 16, 2000 (the “**First Amendment**”) as further amended by that certain SecondAmendment to Lease Agreement dated July 2000, as further amended by that certain Third Amendment toLease Agreement dated January 31, 2001 (the “**Third Amendment**”), as further amended by that certainFourth Amendment to Lease Agreement dated March 22, 2002 (the “**Fourth Amendment**”), as furtheramended by that certain Fifth Amendment to Lease Agreement dated August 31, 2005, executed byLandlord (as successor-in-interest to Original Landlord) (the “**Fifth Amendment**”: all of theforegoing being collectively, the “**Lease**”) pertaining to 51,915 square feet of space (the “**ExistingPremises**”), including the 500 square feet of storage space leased by Tenant pursuant to theOriginal Lease and the 700 square feet of storage space leased by Tenant pursuant to the SecondAmendment (collectively, the “**Existing Storage Space**”) located in that certain building (the“**Building**”) located at 1899 L Street NW, Washington D.C.; and     **WHEREAS**, Landlord and Tenant have agreed that Tenant will expand the Existing Premises, asmore particularly provided for herein.     **NOW THEREFORE,**in consideration of the covenants contained herein and other good and valuableconsideration, the receipt and sufficiency of which is hereby acknowledged, Landlord and Tenanthereby amend the Lease as follows:**A G R E E M E N T**     **1. ****Inclusion of Additional storage Space.** Effective as of January 1, 2006:          (a) An additional 646 square feet of storage space known as LL-9 (the “**LL-9 Storage Space**”)shall be added to and constitute a part of the Premises, subject to all of the terms and conditionsof the Lease (including, but not limited to Section 5, except as provided in thisAmendment); and          (b) The rentable area of the Premises shall be increased by six hundred forty-six (646) squarefeet, and therefore, the total rentable area of the Premises shall be fifty-two thousand fivehundred sixty-one (52,561) square feet.     **2. ****Inclusion of Additional Second Floor Premises.** Effective as of the Additional SecondFloor Premises Commencement Date (defined below):          (a) The second floor of the Building containing 10,104 square feet, as shown on the planattached hereto as Exhibit A-1 (the “**Additional Second Floor Premises**”); shall be added toand
 

 
constitute a part of the Premises, subject to all of the terms and conditions of the Lease(including, but not limited to, Section 5, except as provided in this Amendment; and          (b) The rentable area of the Premises shall be increased by ten thousand one hundred four(10,104) square feet, and therefore, effective on the Additional Second Floor Premises CommencementDate, the total rentable area of the Premises shall be sixty-two thousand six hundred sixty-five(62,665) square feet.     **3. ****Extension of Term.** The Expiration Date of the Lease, as set forth in Paragraph1.5 of the Original Lease, as amended by Paragraph 4 of the Third Amendment, ishereby extended from May 31, 2007 to January 31, 2008 (the “**Extension Period**”).     **4. ****Occupancy Dates and Term.**          (a) The term (the “**LL-9 Storage Space Term**”) of the leasing of the LL-9 Storage Space shallcommence on January 1, 2006 and shall be coterminous with the Term of the Lease (January 31, 2008),as set forth in Paragraph 3 above.          (b) The term (the “**Additional Second Floor Premises Term**”) of the leasing of the AdditionalSecond Floor Premises shall commence on and shall be the date that is fifteen (15) days after thetenant occupying the Additional Second Floor Premises as of the date hereof vacates the AdditionalSecond Floor Premises (the “**Additional Second Floor Premises Commencement Date**”), provided Landlordwill use commercially reasonable efforts to notify Tenant of the Additional Second Floor PremisesCommencement Date at least twenty (20) days prior to such date. Landlord anticipates that thedelivery date will occur around June 1, 2006. Unless sooner terminated pursuant to the provisionsof the Lease, the term of the leasing of the Additional Second Floor Premises shall be coterminouswith the Term of the Lease (January 31, 2008), as set forth in Paragraph 3 above, and theperiod from the Additional Second Floor Premises Commencement Date to the last day of the twelfth(12th) full calendar month following the calendar month in which the Additional SecondFloor Premises Commencement Date occurs shall be the first “**Lease Year**” of the Additional SecondFloor Premises Term. Thereafter, each consecutive twelve (12) calendar month period during theAdditional Second Floor Premises Term shall constitute one (1) Lease Year. Notwithstandinganything contained herein to the contrary, if the Additional Second Floor Premises CommencementDate occurs on the first (1st) day of a calendar month, the first Lease Year during theAdditional Second Floor Premises Term shall be twelve (12) full calendar months.     **5. ****Rent for LL-9 Storage Space.** The Rent during the LL-9 Storage Space Term for theLL-9 Storage Space shall be as follows:             **Applicable**      **Period** **Annual Rent** **Monthly Rent** **Per Square Foot**1/1/06 – 12/31/06 $11,628.00  $969.00  $18.00 1/1/07 – 12/31/07 $11,918.76  $993.23  $18.45 1/1/08 – 1/31/08 $12,215.88  $1,017.99  $18.91 
 

 
     **6. ****Rent for Additional Second Floor Premises.** Subject to Paragraph 10(c) below,effective as of the Additional Second Floor Premises Commencement Date, Rent for theAdditional Second Floor Premises only shall be as follows:             **Applicable**      **Period** **Annual Rent** **Monthly Rent** **Per Square Foot**Lease Year 1 $383,952.00  $31,996.00  $38.00 Lease Year 2(to be prorated) $393,550.80  $32,795.90  $38.95      **7. ****Rentfor Existing Premises (other than Additional Third FloorPremises)****.** The Rentduring the Extension Period for each portion of the Premises other than the LL-9 StorageSpace, the Additional Second Floor Premises and the Additional Third Floor Premises (asdefined in this Fifth Amendment) shall be as follows:                   **Annual Rent** **Monthly Rent**      **Existing Premises** **Existing Premises** **Existing Premises**    **(excluding** **(excluding** **Per Square Foot**    **Existing Storage** **Existing Storage** **(excluding**    **Space and** **Space and** **Existing Storage**  **Applicable** **Additional Third** **Additional Third** **Space and Additional** **Existing****Period** **Floor Premises)** **Floor Premises)** **Third Floor Premises)** **Storage Space**6/1/07 – 01/31/08 $1,632,880.68  $136,073.39  $35.88  $2,067.75/mo.  (to be prorated)                 **8. ****Rent for Additional Third Floor Premises.** The Rent during the Extension Period forthe Additional Third Floor Premises shall be as follows:                       **Additional Third**          **Floor Premises Per****Applicable Period** **Annual Rent** **Monthly Rent** **Square Foot**6/1/07 – 12/31/07 $196,110.00  $16,342.50  $37.67   (to be prorated)        1/1/08 – 1/31/08 $201,003.72  $16,750.31  $38.61   (to be prorated)             **9. ****Operating Expenses and Real Estate Taxes; Adjustment of Additional Rent.**As of the Additional Second Original Floor Premises Term, Tenant’s “pro rata share” referencedin Paragraph 2.2(a)(iii) of the Original Lease, as amended, shall be increased from“39.13%” to “46.76%”. For purposes of Paragraph 2.2(a)(iii) of the Original Lease, the“Base Year” shall continue to be the 2000 calendar year with respect to the original 23.45%, andshall continue to be the 2001 calendar year with respect to the 7.77% relating to the12th Floor Premises added pursuant to the Third Amendment, and shall continue to be the2002 calendar year with respect to the 3.95% relating to the Additional Seventh Floor Premisesadded pursuant to the Fourth Amendment and shall continue to be calendar year 2006 for
 

 
the Third Floor Premises added pursuant to the Fifth Amendment, but the “Base Year” with respect to theadditional 7.63% relating to the Additional Second Floor Premises shall be calendar year 2006.     **10. ****Acceptance of the Additional Second Floor Premises.**          (a) Tenant acknowledges that Tenant has inspected and is fully familiar with the AdditionalSecond Floor Premises and, Tenant shall accept the same in its broom clean, “as is” conditionsubject to Landlord’s repair obligations in Section 3.3 of the Original Lease.          (b) If Tenant makes alterations, including, without limitation, the installation of a securityaccess system, to the Premises in accordance with the Lease generally and with Section 4.1in particular during the period from the Additional Second Floor Premises Commencement Date untiltwelve (12) months after the Additional Second Floor Premises Commencement Date (the “**ContributionPeriod**”), and provided Tenant is not in default under the Lease, Landlord shall contribute the sumof (a) $58,098.00 (the “**Improvement Contribution**”) plus (b) the Additional Improvement Contribution(as defined below), if applicable, towards the cost of said work. Tenant shall have the right,without the need to receive the consent of Landlord, to retain a general contractor selected byTenant to perform such alterations, provided Tenant notifies Landlord of the name of such generalcontractor and general contractor is licensed, bonded and insured to do business in the District ofColumbia. Within ten (10) days after Tenant’s completion of the alterations made during theContribution Period (but in no event later than twelve (12) months after Additional Second FloorPremises Commencement Date), Tenant shall submit to Landlord a detailed breakdown of the costs ofsaid alterations, together with final lien waivers, contractors’ affidavits and architects’certificates, in each case to the extent applicable, in such form as may be reasonably required byLandlord and any other documentation required at the completion of alterations pursuant to theLease. Landlord shall pay to Tenant (up to the sum of (a) the Improvement Contribution andAdditional Improvement Contribution, if applicable) the amount incurred by Tenant in theperformance of the alterations made during the Contribution Period within thirty (30) days afterreceipt of the documentation required in the immediately preceding sentence. Tenant shall not beentitled to any portion of the Improvement Contribution and/or Additional Improvement Contributionnot used in the performance of alterations during the Contribution Period. Landlord shall not beentitled to any compensation or fee in connection with the alterations performed by Tenant.          (c) At Tenant’s option, Landlord shall contribute, upon ten (10) days prior written notice, upto $17,682.00 (the “**Additional Improvement Contribution**”) in addition to the ImprovementContribution set forth above. If Landlord makes the Additional Improvement Contribution, theMonthly Rent for Additional Second Floor Premises the shall be increased by an amount required toamortize, in equal, consecutive payments the Additional Improvement Contribution including interestat the rate of eight percent (8%) per annum over the Additional Second Floor Premises Term.     **11. ****Parking Spaces.** The number of unreserved parking spaces to be made available by Landlord to Tenant pursuant toParagraph 11.2 of the Lease is hereby increased from “forty-four (44)” to “fifty-one (51)”.Tenant’s rights to the seven (7) additional spaces shall terminate if Tenant does not notifyLandlord in writing of Tenant’s exercise of such rights on or before August 31, 2006.     **12. ****Modification of Extension Option.** Tenant’s option to extend the Term provided inParagraph 1.6 of the Original Lease, as amended by Paragraph 5 in the ThirdAmendment, shall remain in full force and effect, except that (a) the Extended Term (asdefined in the Third Amendment) shall commence on February 1, 2008 and shall expire on January31, 2013, and (b) the period during which the option must be exercised shall be from August 1,2006 to January 31, 2007. Additionally, in Section 1.6 of the Original Lease, “fair marketrental of the Premises as of the date of Tenant’s exercise of the
 

 
extension option” is hereby deleted and replaced with “fair market rental of the Premises as of the commencement date ofthe Extended Term”.     **13. ****As-Built Plans.** Landlord shall, at its sole cost and expense, provide Tenant withcopies of all of Landlord’s as-built plans in the possession of Landlord’s architect,including mechanical and electrical, required by Tenant’s architect in connection withTenant’s alterations of the Additional Second Floor Premises.     **14. ****Broker Warranty.** Landlord and Tenant each warrant that it has had no dealings withany broker, agent or any other person in connection with the negotiation or execution of thisAmendment other than Studley Inc., and Transwestern Commercial Services (collectively, the“**Brokers**”). Landlord and Tenant agree to indemnify and hold harmless the other from andagainst any and all cost, expense, or liability for commissions or other compensation andcharges claimed by any broker or agent (other than the Brokers) with respect to this Amendmenton account of the acts of the indemnifying party.     **15. ****ERISA.** Tenant hereby represents and warrants to Landlord that          (a) Tenant is not a “party in interest” (within the meaning of Section 3(14) of the EmployeeRetirement Income Security Act of 1974, as amended) or a “disqualified person” (within the meaningof Section 4975 of the Internal Revenue Code of 1986, as amended) with respect to The MetropolitanLife Retirement Plan for United States Employees, and (ii) no portion of or interest in the Leasewill be treated as the asset of any (a) “employee benefit plan” (within the meaning of Section 3(3)of the Employee Retirement Income Security Act of 1974, as amended), (b) “plan” (within the meaningof Section 4975(e)(1) of the Internal Revenue Code of 1986, as amended, or (c) entity whoseunderlying assets include “plan assets” by reason of a plan’s investment in such entity ; and          (b) Neither Tenant nor any ten percent (10%) or greater owner of Tenant owns, directly orindirectly, more than ten percent (10%) of (i) any class of stock of Metropolitan Life InsuranceCompany or any affiliate of Metropolitan Life Insurance Company; or (ii) any class of stock ofBlackRock Realty Corporation or any affiliate of BlackRock Realty Corporation (including PNC Bank).     **16. OFAC Compliance.**          (a) Each party represents and warrants to the other party that it is (i) not currentlyidentified on the Specially Designated Nationals and Blocked Persons List maintained by the Officeof Foreign Assets Control, Department of the Treasury (“**OFAC**”) and/or on any other similar listmaintained by OFAC pursuant to any authorizing statute, executive order or regulation(collectively, the “**List**”) and (ii) not a person or entity with whom a citizen of the United Statesis prohibited to engage in transactions by any trade embargo, economic sanction, or otherprohibition of United States law, regulation, or Executive Order of the President of the UnitedStates.          (b) Tenant represents and warrants to Landlord that (i) none of the funds or other assets ofTenant constitute property of, or are beneficially owned, directly or indirectly, by any EmbargoedPerson (as hereinafter defined), and (ii) none of the funds of Tenant have been derived from anyunlawful activity with the result that the investment in Tenant is prohibited by law or that theLease, as amended and/or extended, is in violation of Applicable Law. The term “**Embargoed Person**”means any person, entity or government subject to trade restrictions under U.S. law, including butnot limited to, the International Emergency Economic Powers Act, 50 U.S.C. §1701, etseq., The Trading with the Enemy Act, 50 U.S.C. App. 1, etseq., and anyExecutive Orders or regulations promulgated thereunder with the result that the investment inTenant is prohibited by any Applicable Law or Tenant is in violation of any Applicable Law.
 

 
          (c) Each party covenants and agrees with the other party (i) to comply with all ApplicableLaws relating to money laundering, anti-terrorism, trade embargos and economic sanctions, now orhereafter in effect, (ii) to promptly notify the other party in writing if any of therepresentations, warranties or covenants set forth in this sub-paragraph or the precedingsub-paragraphs are no longer true or have been breached or if such party has a reasonable basis tobelieve that they may no longer be true or have been breached, (iii) not to use funds from any“Prohibited Person” (as such term is defined in the September 24, 2001 Executive Order BlockingProperty and Prohibiting Transactions With Persons Who Commit, Threaten to Commit, or SupportTerrorism) to make any payment due to the other party under the Lease, as amended and/or extended,and (iv) at the reasonable request by a party, to provide such information as may be requested bysuch party to determine the other party’s compliance with the terms hereof.          (d) Each party hereby acknowledges and agrees that its inclusion on the List at any timeduring the Term shall be a material default of the Lease. Notwithstanding anything herein to thecontrary, Tenant shall not permit the Premises or any portion thereof to be used or occupied by anyperson or entity on the List or by any Embargoed Person (on a permanent, temporary or transientbasis), and any such knowing use or occupancy of the Premises by any such person or entity shall bea material default of the Lease.     **17. ****Definitions****.**Unless the context otherwise requires, any capitalized term used hereinshall have its respective meaning as set forth in the Lease.     **18. ****Integration of Amendment and Lease****.**This Amendment and the Lease shall be deemed tobe, for all purposes, one instrument. In the event of any conflict between the terms andprovisions of this Amendment and the terms and provisions of the Lease, the terms andprovisions of this Amendment shall, in all instances, control and prevail.     **19. ****Counterparts.** This Amendment may be executed by each of the parties hereto in separate counterparts and havethe same force and effect as if all of the parties had executed it as a single document.     **20. ****Ratification.** Except as modified herein, all of the remaining terms and provisionsof the Lease shall remain in full force and effect.[**signature page follows**]
 

 
     **IN WITNESS WHEREOF**, Landlord and Tenant have duly executed this Amendment as of the dayand year first above written.             **LANDLORD:**             **1899 L STREET TOWER LLC**,