You'd think sand would be a good way to loosen clay soil before planting a new lawn. It can be but only in large quantities. A little bit is usually counter-productive.
How to Till a Lawn (with Pictures) - wikiHow
1. Soils & Plant Nutrients NC State Extension Publications
How to Seed a Lawn - This Old House
How to Get New Grass to Grow in the Heat of Summer: Seed With Potting Soil
To Till or Not to Till the Garden - Northern Homestead
Using COMPOST to cover GRASS seed / Lawn GOALS start with this
Soil Amendement Basics - Resource Central
How to Create Organic Soil for Your Healthiest Garden Ever
Screened Topsoil Organic Garden Mix Better Earth Compost, 55% OFF
Complete Beginner's Guide to the Best Raised Bed Soil
Beware: This Manure Will Destroy Your Garden - Tenth Acre Farm
How To Improve Clay Soil Loosen, Aerate Compacted Soil
How to Use Mulch for Low Maintenance Gardening
JRK Sandy Soil Grass Seed Mix - 5 lbs : Patio, Lawn & Garden
Can I Mix Left-over Sand Into My Soil Before Planting New, 59% OFF