Design a poster
Have you seen awareness campaigns about changing people's behaviour - e.g. stopping drink driving, ending bullying at school, preventing the spread of HIV? Posters can help people to think for a moment about the way they behave, and challenge them to change their behaviour.
You could design a poster to challenge prejudice. Do you have a problem with prejudice in your street, local area, school, or group? Your poster could be used as a 'reminder' for your own group, or as a challenge to the public.
You could ask your school, or write to your local civic authority (the place that administrates public services in your area) and tell them you think it is necessary to display your poster. Make sure you always ask the appropriate permission before putting it up.
You can always ask people you know to display it:
A local shopkeeper
A minibus owner
A friend with a house on a busy road
Don't forget that just showing your poster to friends, family and peers, and talking about prejudice, will help to spread the message in your community.