How can you tell whether grammar school is right for your child? The short and flippant answer is that you can't! The more helpful answer is that with a little effort you can get a broad idea on whether there is a reasonable chance of acceptance.
Some parents make the decision that the best way of applying for grammar school is not to do any particular preparation. They fear that if the children are pushed too hard to pass, they might then struggle at grammar school because their test result did not truly reflect their ability. Whilst I have some sympathy with this argument, I would argue that by being completely unprepared on what to expect they will not be playing on a level playing field and are likely to perform below their 'natural ability'.
That's isn't to say that children need to have a lot of intensive tuition or that it necessarily costs a lot of money. There are things you can do yourself to help such as getting some practice papers (of the right type!) to let your child have a practice with the kind of test they will get for the real thing in September. You may want to go through these yourself with your child if you are reasonably confident. If not, you might want to consider getting a tutor. You can read more about making this kind of decision on our previous article.
Bear in mind that practice papers vary in difficulty - so you may find your child scoring highly on some papers and doing not so well on others. This means it's hard to know what kind of raw percentage is likely to secure a grammar school place. Very broadly speaking a mark of over 70% suggests a reasonable chance - but you may be looking at marks of 90% or more for the 'higher ranked' grammar schools.
Places are allocated in grammar schools using ranking, so your child's position will be based on comparison with other children taking the same test. Getting this kind of comparison guide is clearly going to be difficult on your own. This is where professionally run mock mornings run under examination conditions can be really helpful as they get your child used to the test conditions and some may give your child's rank compared to the others taking the test.
Finally, it's worth remember that not every child that applies to grammar school will be accepted. Not securing a place should in no way be seen as failure. Gloucestershire has some excellent comprehensive schools which may suit many children better than a grammar school. Why not look round a range of schools and see what suits your child before deciding that grammar is the only way!