If the question is "Are black three year old kids choosing to be bad kids more often than white three year old kids?" then I thought I had answered it.
The short answer is I don't know, based on the evidence provided.
The medium length answer is I don't know - there's not even enough data to conclude that race is a factor at all, either in the behaviour of the children or in the reaction of the teachers
The long answer is as explained above.
To put it into more concrete terms, suppose (and this is just a hypothetical example) that the exact same data is re-analaysed but instead of dividing it up as black v white, it is divided up as, say, single parent parent family v two parent family. And suppose the data showed that despite single parent families being a minority, 90% of those suspended came from single parent families. Then I think it would be reasonable to assume that this was the predominant factor in what leads some children to be suspended and others not, and the colour of the children was just a red herring.
Where to start:
Children who are being abused or neglected at home tend to have behavior problems. This is not limited to single parent homes nor is it limited to families of certain racial or ethnic groups nor is it limited to certain socioeconomic groups.
You know who else has behavior problems? Children who are over indulged.
Children of single mothers are often assumed to be lacking in certain skills and to have more behavior problems, regardless of race, socioeconomic or educational status. Singleothers are often assumed to be irresponsible and promiscuous even when divorced or widowed.
Perhaps I am misunderstanding your post bit there seems to be an implication that black families have more children than white families. In my observation (living in a highly catholic area) children from large families are generally well behaved, know how to share and get along with others.
In my experience, teachers and schools do often have favorites and scapegoats. They often make some pretty broad assumptions about a students behavior and abilities based upon how a child (and patens) dress, perceived socioeconomic and educational status of the parents, marital stays of the parents, and yes: race of child and parents.