This is a pretty comprehensive site for Illinois schools. Click on the link and it will take you to Grayslake schools.
You can cut and paste this link. http://www.d46.k12.il.us/images/d46map07.jpg
This will show you the district boundaries for the grade schools in Grayslake. Grayslake has two high schools. Normally those that live south of Washington will go to Grayslake Central. Those that reside to the north of Washington in the Grayslake High School District will go to the Grayslake North High School. There is a map for the high schools at http://www.d127.org/pdf/d127/maph.pdf. It is difficult to read. You best bet is to call District 127 at 847-986-3400.
You can view the report cards for the Grayslake high schools at http://www.d127.org, the grade schools at http://www.d46.k12.il.us/district.
Also greatschools.com is a great resource.
A site I recommend to many clients is http://www.greatschools.net. It's been a consistent award-winning site and most recently won a People's Choice Webby award as the "Best Family & Parenting Site".
Trulia's real estate guide might be able to help. You can plot schools on the map and get information about them, including contact information.