TRAUMA'S IMPACT ON LEARNING
The human brain, especially the developing brain, is plastic and adaptable. It is the brain’s plastic quality that allows us to learn, grow, and adapt to new situations. But it is unfortunately this same feature of the brain that causes trauma to have a profound effect on the developing brains of children.
When there are threatening or unpredictable changes in the environment, the brain immediately engages in an "alarm" response. If the threat continues, the brain will then enter either what is commonly referred to as the "flight or fight" response or a "freeze and surrender" response. When engaged in fight or flight, the body is flooded with adrenaline and every sense is attuned to possible threats. When engaged in the "freeze and surrender" response, the body slows down and the individual begins to dissociate or "tune out" from the world.
In many adult brains, or the brain of an individual who has only experienced predictable and infrequent trauma, once the threatening experience passes, the brain returns to a baseline state. However, when a brain is still developing, and when the threats are particularly severe, prolonged, or unpredictable, or if the stress response is evoked over and over, the brain is unable to regulate itself and the smallest trigger can again push the individual into a "fight or flight" or "dissociative" response. One analogy is to compare the stress-state to a groove in a record—the more the record is played, the deeper the groove becomes engraved into the vinyl.
As is well known, the acquisition of academic skills in reading, writing, and mathematics requires “attention, organization, comprehension, memory engagement in learning, and trust.”  Complex childhood trauma, by rewiring the brain so that the triggered fight or flight and dissociative responses are easily triggered, impairs students’ ability to operate in each of these areas.
What's more, Complex trauma often induces behaviors—including aggression, disproportionate reactiveness, impulsivity, distractibility, or withdrawal and avoidance—that disrupt the learning environment and frequently lead to exclusionary school discipline measures or absence from school. These barriers have tragically predictive consequences for students: academic research has extensively documented the link between trauma and poor academic outcomes, including failure to reach proficiency and failure to graduate from high school.
According to published research, children who have suffered three or more traumatic experiences are:
Two-and-half times more likely to repeat a grade than are children who have experienced none; 
Five times more likely to have severe attendance issues;
Six times more likely to experience behavioral problems; and
More than twice as likely to be suspended from school.
Fortunately, the effects of childhood trauma can be mitigated and even reversed. Interventions that draw on the resilience of young people have been shown to be highly effective.