It is definitely an assessment, but quite what this means varies between schools.
Some schools are not significantly over-subscribed. They will just be looking to see your DD behaves in an age appropriate way....that she isn't overly aggressive and is fairly biddable. It is just a chance for them to spot anyone who is likely to be significantly hard work to be honest.
Other schools which are highly selective will be looking for biddable children, but also those who are mature - can sit still and listen, join in and take turns, who have got some basic skills such as describing pictures with a good voculary, using numbers, perhaps scissors, some drawing skills.....they are looking for those who seem to be able and also very teachable, rather than difficult.
Some parents believe it or not choose their nurseries or even 'play tutors' because they will prep their little girls for this kind of assessment and familiarise them with the skills and behaviours schools a re looking for. Are you feeling worried because you are concerned that your DD might not perform well, or worried that you haven't prepared her when others might have prepared their DDs, or just about the concept of little children being assessed?
It's pretty close now, so I'd just go ahead with it. The list of possible activities a PP mentioned is a good one to consider. You can do a little low level work with your DD, but the fact you haven't spent months on it isn't something to worry about. Just trust in your DD and that if this is the right school she will get a place....there is nothing you can really do anyway at this stage, and unless it's highly selective and very competitive, your DD will probably charm them and be offered a place.
Check she can do the following things;
- give her name as both first name and surname
- say how old she is and where she lives and say a few things about toys or acitivities she enjoys.
- describe a picture
- say something about a story she has enjoyed
- ideally sit and listen and wait her turn
- draw a picture of a person with features such as separate body and head or a house
- recognise some numbers and count a small number of items fairly accurately.
Practising some of these things in a very low key way isn't a bad idea, or asking her to do them and particularly if she doesn't understand what is being asked, you then showing her/doing it can help......because sometimes children are perfectly able to do all the things I mention, but do t demonstrate them just because they aren't familiar with what those activities/tasks might be called or how someone might ask them to do it. But really, once or twice is fine for this.....don't go overboard.
If she can't do some of these things at the moment, don't worry and try not to give any sense that she's going to a test of sorts. Just encourage her to be friendly and to listen and join in. She can only be who she is...and that's just fine!