In case my link didn't work here are the two properties I suggest you check out;
I have created a custom search for you, with the following criteria I got from your question;
- Rental Homes only
- 3 or 4 bedrooms
- Max price = $900/month
- Near to good schools
- Situated around Tomball, TX as far out as Magnolia, TX and Cypress, TX.
Here is what I have found: http://bit.ly/RTBdaZ
The green box represents the areas that you specified, the green pins are 9+ rated schools (according to greatschools.org) and the blue markers represent properties that fit your search.
There are two properties priced at $900/month and $771/month towards the southeastern corner of your preferred area. I'd recommend that you investigate those properties and contact an agent to help you with your very specific home search.
I wish you the very best of luck and hope you find your new home soon.