This is also something that is in the Naplan tests in the form of a writing test. I've mentioned before this link to Pascal Press which has free downloadable sample writing tests and answers for each graded level.
Here are some topics from those samples, some past tests and some of our own ideas too.
Hats should not be compulsory at schools.
Life is easier today than in the past.
Dogs are a better pet than cats.
Cats are a better pet than dogs.
Every child should have a pet.
School uniform should be compulsory.
All children should have to play sport.
Boys and girls should not be allowed to eat sugar.
Junk food- should it be banned at school?
Recycling is the most important thing we can do as a family.
Computer games- are they a waste of time?
What is more important- friends or family?
Caged or free- should animals be kept in zoos?
Climate change- man made or natural?
Graffiti- is it art or vandalism?
Reading books is better than watching TV.
Shoes should not be compulsory at school.
Everyday people waste power, we should save electricity when possible.
It is better to live in the city than the country.
It is better to live in the country than the city.
If you fail something you should give up.
School should run seven days a week.
Maths is tricky- schools should stop teaching it.
Spelling is tricky- we shouldn’t worry about spelling.
Everybody is equal- this is the most important thing for all of us.
Sharing- we should share everything with everyone.
Fresh air- every child should spend half their day outside.
Rest is important- every student should go to bed at 8pm.
Stop school break time- we should have more time studying.
Here is a site with some ideas on how to structure an argument.
I hope this gives a few ideas for topics you can bring up with your kids to help them practice arguing their opinions!
Jill and Euan