AMENDMENT NO. 3 TO CREDIT AGREEMENT

Exhibit 10.24

Execution Copy

AMENDMENT NO. 3 TO CREDIT AGREEMENT

     This AMENDMENT NO. 3 TO CREDIT AGREEMENT (this “ Agreement ”) is entered into as of April 30, 2009 (the “ Effective Date ”), by and among STUDY ISLAND, LLC, a Delaware limited liability company (“ Borrower ”), the other person designated as a “Credit Party” on the signature pages hereof, the financial institutions designated as “Lenders” on the signature pages hereof (“ Lenders ”) and GENERAL ELECTRIC CAPITAL CORPORATION, a Delaware corporation (“ Agent ”), for itself as a Lender (including as Swingline Lender) and L/C Issuer and as Agent for Lenders. Unless otherwise specified herein, capitalized terms used in this Agreement shall have the meanings ascribed to them in the Credit Agreement (as hereinafter defined).

RECITALS

     WHEREAS, Borrower, the other Credit Party, Agent and Lenders have entered into that certain Credit Agreement, dated as of November 16, 2007, amended by that certain Amendment No. 1 to Credit Agreement, dated as of May 21, 2008 and that certain Amendment No. 2 to Credit Agreement, dated as of February 18, 2009 (as amended, restated, amended and restated, supplemented or otherwise modified from time to time, the “ Credit Agreement ”); and

     WHEREAS, Borrower, Agent and Lenders have agreed to amend certain terms of the Credit Agreement as described herein.

     NOW THEREFORE, in consideration of the mutual execution hereof and other good and valuable consideration, the receipt and sufficiency of which is hereby acknowledged, the parties hereto agree as follows:

     SECTION 1. Definitions . Capitalized terms used in this Agreement, unless otherwise defined herein, shall have the meaning ascribed to such terms in the Credit Agreement.

     SECTION 2. Amendments to Credit Agreement . Subject to the satisfaction of the conditions precedent set forth in Section 4 hereof, the Credit Agreement is hereby amended as follows:

as an additional deduction from Current Assets immediately below the deduction for “deferred tax assets.”