A wide range of organizations and services - including many elementary schools - sell or hand out Child Identification Kits which walk parents through the process of collecting finger prints, pictures, hair samples and/or other identifying information for your child. Their purported purpose is to make your child safer by already having in place (often submitted directly and immediately to the school or police department) all the information potentially needed to help locate your child should they be kidnapped or go missing.
This is a very bad idea. Please do not comply!
Although many organizations do actually believe they are helping, you are putting your child at risk by participating in these programs. There are no laws protecting your child's information once it has been submitted; in fact, the laws on the books allow that information to passed along - without your knowledge or consent - to multiple government (and pseudo-governmental) agencies and researchers for a variety of uses. This is not fear-mongering; I was startled enough when I found out about these that I have actually done the research. This is happening in our country right now to many people's detriment.
If you genuinely feel you must have one of these kits made up for your child, keep it in a safe place only you can access (think home safe or safe deposit box). Should something ever actually happen to your child, you'll still have all the relevant information immediately available, without having unnecessarily exposed your child's private personal information to misuse.