EMPLOYMENT AGREEMENT

Exhibit 10.15

Study Island, LLC

EMPLOYMENT AGREEMENT

This Employment Agreement (this “Agreement”) is entered into as of this 22nd day of May, 2007, by and between Study Island LLC, a Delaware limited liability company (the “Company”), and James B. Walburg (the “Executive”).

WHEREAS, the Company desires to engage the services of the Executive and the Executive desires to be employed by the Company;

WHEREAS, the Company desires to be assured that the unique and expert services of the Executive will be available to the Company, and that the Executive is willing and able to render such services on the terms and conditions hereinafter set forth;

WHEREAS, the Company desires to be assured that the confidential information and good will of the Company will be preserved for the exclusive benefit of the Company.

NOW, THEREFORE, in consideration of such employment and the mutual covenants and promises herein contained, and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the Company and the Executive agree as follows:

The Company will employ the Executive in the position of Senior Vice President, Chief Financial Officer, beginning on May 29, 2007 (the “Start Date). The Executive shall report to the Chief Executive Officer. The Executive will have such authority, and will perform all of the duties, normally associated with this position as well as other duties as may be reasonably assigned to him from time to time by the Board of Managers of the Company (the “Board”) or the Chief Executive Officer, in each case consistent with his position as Senior Vice President, Chief Financial Officer.

The Executive will devote all of his business time, ability, attention and best efforts to the performance of his duties hereunder in a manner which will faithfully and diligently further the Company’s business to the exclusion of all other business activities. However, the Executive may devote reasonable periods of time to engaging in charitable or community service activities, so long as none of these activities interfere with his duties under this Agreement. Executive agrees to perform his duties and responsibilities within Company policies, standard work hours and attendance and general work practices.

The Executive’s employment hereunder initially shall be for a term commencing on the Start Date and ending on the day preceding the second anniversary of the Start Date, subject to earlier termination in accordance with Section 6 below. The Agreement shall be automatically extended from year to year thereafter unless either party gives not less than sixty (60) days prior written notice to the other that such party elects to have the Agreement terminated effective at the end of the initial or then current renewal term. The provision of the foregoing notice shall

result in the expiration of this Agreement at the end of the then current term and shall not be deemed a termination of Executive’s employment by the Company.

During the term of employment under this Agreement, the Company agrees to pay to the Executive, and he agrees to accept in full consideration for all services performed by him, the following compensation:

4.1 Base Salary: The Company will pay the Executive an annual base salary of Two hundred thousand dollars ($200,000), before all customary payroll deductions. This annual base salary will be paid in accordance with the usual payroll practices of the Company. The Board may make such increases in the base salary as the Board may, in its sole discretion, deem appropriate.

4.2 Bonus: During the Executive’s employment term, the Executive will participate in the Company-wide bonus plan in which all employees of the Company participate based on the bonus plan’s policies and procedures then in effect. In addition, Executive will be eligible to receive in respect of each fiscal year of the Company (commencing with the fiscal year ending on December 31, 2007) an annual bonus in an amount equal to up to 40% of his earned base salary (pro rated for partial years) based on, among other things, performance targets established by the Board of Managers by reference to the operating plan approved from time to time by the Board of Managers; provided that if the performance targets in any fiscal year are exceeded, the maximum bonus the Executive shall be eligible to receive shall equal up to 50% of his base salary.

4.3 Incentive Equity: On the Start Date, Executive will be granted incentive equity pursuant to the long term incentive equity program of the Company’s parent company, Study Island Holdings, LLC (“Holdings”), on the terms and conditions set forth in Exhibit A.

4.4 Withholding: The Company may withhold from any compensation and benefits payable to the Executive all applicable federal, state and local withholding taxes.

4.5 Board Participation. The Executive will not be a member of the Board of Managers of Holdings but will be permitted to attend and participate in meetings of the Board of Managers of Holdings, with the exception of any closed executive sessions.

5.1 Description of Benefits: During the term of employment under this Agreement, the Executive will be entitled to participate in all employee incentive, pension and welfare benefit plans and programs made available generally to other senior executives of the Company, as such plans or programs may be in effect from time to time (including, without limitation, incentive equity, profit sharing, savings and other pension and retirement plans or programs, medical, dental, hospitalization, short-term and long-term disability and life insurance plans, accidental death and dismemberment protection, and any other pension or retirement plans or programs and any other employee incentive compensation plans, employee welfare benefit plans or programs that may be sponsored by the Company from time to time and provided that

Executive meets the eligibility requirements and other terms, conditions and restrictions of the respective plans and programs, including any plans that supplement the above-listed types of plans or programs, whether funded or unfunded). Payment for such coverages will be the sole responsibility of the Executive, unless the Company makes such coverages available to similarly situated executives on a shared cost basis. In addition, the Executive will be entitled to 4 weeks of paid vacation per year. During 2007, as part of the Executive 4 weeks of paid vacation per year, the Company will permit the Executive to take a week vacation the week of July 20 – July 27 and will use reasonable efforts to permit vacation on August 2 and 3. The Company will pay for all reasonable expenses actually incurred by the Executive directly in connection with the business affairs of the Company and the performance of his duties hereunder, upon presentation of proper receipts or other proof of expenditure and subject to such reasonable guidelines or limitations provided by the Company from time to time.

The Executive’s employment under this Agreement may be terminated as follows, but in the event of any such termination, the provisions of Sections 7 and 8 will survive the termination of the Executive’s employment.

6.1 By the Company: The Company may terminate the employment of the Executive, with or without Cause (as defined in Section 7.5 hereof), at any time during the term hereof by delivery of a Notice of Termination (as defined below) to the Executive.

6.2 By the Executive: The Executive may terminate his employment at any time, for any reason, by delivery of a Notice of Termination to the Company.

6.3 Death; Disability: The Executive’s employment will terminate automatically upon the Executive’s death or total disability. The term “total disability” will mean the Executive’s inability to perform the duties set forth in Section 1 hereof for a period of twelve (12) consecutive weeks, or a cumulative period of 90 business days in any 12-month period, as a result of physical or mental illness or loss of legal capacity.

6.4 Notice: The term “Notice of Termination” means at least thirty (30) days’ prior written notice of termination of the Executive’s employment (the “Advance Notice Period”), during which period the Executive’s employment and performance of services will continue; provided, however, that (i) the Executive may, upon termination of his employment for Good Reason, make such notice effective immediately, (ii) the Company may, upon termination of his employment with or without Cause, make such notice immediately and (iii) the Company may, upon notice to the Executive and without reducing compensation during any Advance Notice Period, excuse him from any or all of his duties during any Advance Notice Period. The effective date of termination of employment (the “Termination Date”) will be the date on which such Advance Notice Period expires (or the date of notice, if the Company exercises its rights under clause (ii) hereof or if the Executive exercises his rights under clause (i) hereof) or as otherwise provided in Section 3 above.

In the event of termination of the employment of the Executive, all compensation and benefits set forth in this Agreement will terminate as of the Termination Date except as specifically provided in this Section 7:

(a) If the Company terminates the Executive’s employment without Cause (other than as result of death or total disability), he will not be entitled to receive any of the payments or benefits provided for herein except the Company shall (i) pay his base salary through the Termination Date, (ii) pay his base salary during the Severance Period (as defined in Section 7.7 below) payable at the same time such payment would be made during Executive’s regular employment with the Company, (iii) provide Executive with all benefits that are accrued but unpaid as of the Termination Date, and (iv) provide the Executive with all benefits expressly available upon termination of employment in accordance with the plans and programs of the Company applicable to the Executive on the Termination Date (but without duplication of any benefits or payments otherwise provided for hereunder).

(b) If the Company terminates the Executive’s employment for Cause, he will not be entitled to receive any of the payments or benefits provided for herein except the Company shall (i) pay his base salary through the Termination Date, (ii) provide the Executive with all benefits that are accrued but unpaid as of the Termination Date, and (iii) provide the Executive with all benefits expressly available upon termination of employment in accordance with the plans and programs of the Company applicable to the Executive on the Termination Date (but without duplication of any benefits or payments otherwise provided for hereunder).

(a) If the Executive’s employment is terminated pursuant to Section 3 hereof as a result of the expiration of the term of this Agreement, he will not be entitled to receive any of the payments or benefits provided for herein except the Company (i) pay his base salary through the Termination Date, (ii) pay his base salary during the Severance Period payable at the same time such payment would have been made during the Executive’s regular employment with the Company, (iii) provide the Executive with all benefits that are accrued but unpaid as of the Termination Date and (iv) provide the Executive with all benefits expressly available upon termination of employment in accordance with the plans and programs of the Company applicable to the Executive on the Termination Date (but without duplication of any benefits or payments otherwise provided for hereunder).

(b) If the Executive’s employment is terminated pursuant to Section 6.3 as a result of his death or total disability, he will not be entitled to any payments or benefits, except the Company shall (i) pay his base salary through the Termination Date, (ii) provide Executive with all benefits that are accrued but unpaid as of the Termination Date and (iii) provide the Executive with all benefits expressly available upon termination of employment in accordance with the plans and programs of the Company applicable to the Executive on the Termination Date (but without duplication of any benefits or payments otherwise provided for hereunder).

7.4 Payment Schedule: All payments of base salary under this Section 7 (including wages for services performed prior to the Termination Date) shall be paid in accordance with the Company’s normal payroll practices and any bonus amounts due under this Section&nbs