It is known that suitable classroom acoustics is important for effective teaching and learning. To this end, many countries have developed classroom acoustics standards. However, research shows that these standards are often not implemented. Research assessing the implementation of classroom acoustic standards internationally concludes that successful implementation is driven by mandatory standards that are part of the building codes and that the cost of compliance is a barrier. The study presented here explores the cost of upgrading classrooms to achieve a suitable reverberation time. The paper presents a case study in South Africa, where acoustic standards are generally not implemented and cost and know-how are barriers. The objective was to optimize the cost, acoustic benefit, and accessibility of acoustic interventions. Four adjacent similar classrooms were retrofitted with different sound-absorbing ceiling panels that cover a percentage of the ceiling area. The weighted sum model was used to assess the suitability of each intervention, taking into account the cost, acoustic benefit (in terms of reverberation time), and ease of access to materials. The case study demonstrates that a noticeable improvement in acoustic conditions can be achieved without significant cost and provides a basis for further research to develop simple standardized design recommendations.