help me to challenge her mind

DD1 will be 4 next month, and we're at a loss on how to keep her mind active, and challenged. She's a bright spark, she picks things up really quickly when learning, and she's always keen to learn new things. I've recently changed kindy's as the previous one told me that she was 'too advanced' for their 3yr old kindy, but they couldn't move her up to 4yr old kindy yet, and therefore couldn't accommodate her. So I found somewhere who would put her in 4yr old kindy.
At the moment, we practice our letters, numbers, shapes, memory cards, role play activities, arts & crafts, outdoor games etc. Obviously I don't want her to grow up too quick, but at the same time, we can see she needs more.

So, what do you do with your 4yr old? All suggestions would be muchly appreciated :)

do you have any phonics books or basic maths activity books for preschoolers??
we've just started doing basic addition with DD1 and im wanting to get some phonics stuff for her too

Some things we do:

- play numbers games where we count things eg apples and add, multiply and take away.
- write letters to grandparents where I write the letter and she copies it.
- make our own story books where she makes up a story, I write it in a scrap book and she illutrates it. Then I get her to read it to me.
- also act out a lot of stories with toys so she makes up a play and then we act it out with the characters being her toys or us.

Hi Jodi - i don't know if you've heard of the Learning Ladder, but they sell a Starter Stile set, with Pre-Number, Early Number and then moves onto different levels as the children progress.
If you want to have a look, google the learning ladder - have a look at the online catalogue on pages 34/35. I bought them for my older girls, and am using them now with my almost 3 year old (just starting off with the basics)
It's worth having a look.
(i'm not a learning ladder rep or anything lol)