Ramadan is a month-long Islamic festival, during which Muslims fast in the daylight hours. TES Resources has lots material to help teachers organise relevant lessons, as well as assembly ideas for the first day after Ramadan, known as Id-ul-Fitr ("the feast of fast-breaking").
International Youth Day
International Youth Day takes place every year on 12 August when governments worldwide discuss issues affecting young people. There are a number of TES Resources available which cover this topic, including an excellent video from Teachers TV on community cohesion.