Operating income of $9.3 million was $2.7 million lower compared to the prior year quarter as most of the revenue decrease was offset with lower operating expenses. Please note, that some of this operating leverage will reverse in the second half if AIU System maintains normalized operations. Moving on to corporate and other. Operating loss for the quarter was $5.2 million or $7.2 million lower as compared to prior year quarter. This improvement was primarily driven by lower legal expenses. Now to income taxes. For the first quarter, we recorded a provision for income taxes of $13.4 million, which reflects accruals for federal and state corporate net income tax, resulting in an effective tax rate of 25.4%. The effective tax rate for the quarter was positively impacted by discrete items for the tax effect of stock-based compensation and the release of previously recorded tax reserves, which decreased the effective tax rate by approximately 2.5%.
Finally, we expect our full year 2024 effective tax rate to be between 25.5% and 26.5%. Now to our balance sheet and liquidity. For the first quarter, net cash flows from operations were $54.5 million versus $4.6 million in the prior year quarter. The increase in cash flows from operations was primarily driven by the timing of the academic calendar and the session start dates. We ended the quarter with $642.4 million of cash, cash equivalents, restricted cash and available for sale short-term investments. This represents an increase of approximately $38.3 million since the end of last year. Additionally, during the quarter, we returned $14 million to shareholders in the form of quarterly dividends and share repurchases. Capital expenditures for the first quarter are approximately $1.2 million or 0.7% of revenue.
As a reminder, for the full year 2024, we foresee capital expenditures to be between 1% to 2% of revenues. Before I share the updated outlook, let me take a minute to discuss capital allocation. We are pleased to announce that consistent with our dividend policy on May 1st, the Board of Directors approved the first quarter dividend payment of $0.11 per share payable on June 15th, 2024 to the holders of record of Perdoceo’s common stock at the close of business on June 1, 2024. Future quarterly dividend payments are expected to be paid out of free cash flows for the relevant year subject to Board approval and the company’s available retained earnings, financial condition and other relevant factors. Subject to the requirements just mentioned, we expect quarterly dividend payments will be an integral and growing part of our balanced capital allocation strategy and expect the Board to review the current quarterly dividend amount per share this fall.
Separately, during the first quarter of 2024, we repurchased approximately 0.4 million shares at an average purchase price of $17.60 for a total of $6.8 million. Moving forward, we expect share repurchases to remain a meaningful part of our balanced approach to long-term capital allocation. Our capital allocation strategy also prioritizes investments in organic projects, in particular, technology related initiatives designed to benefit our students and maintaining a strong balance sheet, while also evaluating diverse strategies to enhance stockholder value, including acquisitions. Now, let us discuss our outlook for 2024. Based on better than expected performance in the first quarter, we expect full year 2024 adjusted operating income to now range between $175 million and $190 million, as compared to the previously provided range of $170 million to $190 million and the 2023 adjusted operating income of $174.9 million.
Adjusted earnings per diluted share is expected to range between $2.11 and $2.27 versus $2.10 in 2023. This outlook reflects our current beliefs that the high levels of student retention and engagement we experienced over the past few quarters, partly supported by the positive impact from various federal student aid initiatives, will continue to persist through the remainder of 2024. Full year revenue at CTU is expected to be lower than 2023 due to the academic calendar comparability at CTU resulting in the lower revenue days for the current year. Please also note, that if we were to ignore this comparability impact, revenue for CTU would show growth versus 2023. We also expect CTU to experience total enrollment growth for the year end 2024, primarily driven by high levels of student retention and engagement, as well as continued growth from the corporate engagement programs.
At AIU System, revenue is expected to be below 2023 levels due to the lag impact of lower beginning total enrollments. As AIU System continues to operate with normalized levels of marketing and admissions, while also experiencing strong levels of student retention and engagement, we expect the following: The revenue decline at AIU System will moderate each subsequent quarter during the 2024. In the fourth quarter, we expect AIU System to experience revenue and enrollment growth as compared to the fourth quarter of 2023, and for each quarter, we expect AIU system to post double-digit enrollment growth as compared to the year-end 2023. For the second quarter of 2024, we expect adjusted operating income to be in the range of $48 million to $50 million as compared to $55.2 million in the prior year quarter, with adjusted earnings per diluted share to range between $0.57 and $0.59 per diluted share versus $0.61 in the second quarter of 2023.
As a reminder, CTU’s academic calendar may impact the comparability of revenue earning days and enrollment results in any given quarter and year, but not necessarily in the same magnitude and direction. On a full year basis, CTU will have lower revenue earning days in 2024, which will disproportionately impact the first half of 2024 when compared to the prior year. Also, the lag impact from lower beginning total enrollments at AIU System will have a larger impact on the first half of 2024. As a result, we expect the first half adjusted operating income from 2024 to be lower as compared to the first half of 2023, while the second half is expected to show growth as compared to 2023. As disclosed in our most recent Form 10-K, the Department of Education has recently gone through and continues to go through additional negotiated rulemaking processes, while also updating interpretations and providing new guidance on various other topics.
