Thousands of kids from all over the UK have taken to the streets to take part in an attempt to break the world record for the biggest 'walking bus'.
This is when children march along the street in pairs to and from school, with adults making sure they're safe.
Organisers hope 80,000 children will complete Wednesday's walk, smashing the 2005 record of 23,529 walkers.
In 2004 77 children were killed on roads in the UK and a further 2,262 were seriously injured.
The aim of the walk is to make drivers slow down and watch out for children on the roads and pavements.
Witnesses were stationed at every school to count the number of pupils taking part in the walk which began at 10am.
Official record-keepers Guinness will then double check the figures before announcing if the record was broken in a few months time.
During the walk children also learnt the following 'ABC' road safety rules:
- A is for awareness - even if you are careful, drivers might not be, so be aware of what's going on around you.
- B is for behaviour - wear bright clothes in the dark, stay on the pavement and keep your cool. Don't muck around near traffic.
- C is for choice - choose safe places to cross roads, look out for your mates and if you're in the car, make sure adults don't speed