Is zakat due on money derived from a share in a private school, which is then reinvested to increase that share, and is zakat due on school merchandise such as books and school uniforms?

Zakat is obligatory on wealth that has completed a full year (hawl). The fixed assets of a company are not included in the calculation for Zakat. However, items bought for trade, whether books, clothes, or other goods, are subject to Zakat. Zakat on these trade goods is calculated based on their value, not solely on profits.