More than 10,000 school children are set to be trained how to carry out life-saving CPR using a defibrillator.
South Central Ambulance Service (SCAS) staff will lead the training at almost 100 schools across Berkshire, Buckinghamshire, Hampshire and Oxfordshire.
The project coincides with Restart a Heart Day on Wednesday, which is a national campaign to to improve survival rates from out-of-hospital cardiac arrests.
Every year in the UK, nearly 30,000 people suffer a cardiac arrest outside of hospital where CPR is attempted - yet less than one in ten survive.