3 of 4 of my children have low hemoglobin, hematocrit, mcv, mcvh....high rdw. i believe that affect their education performance and behavior.

See doctor ASAP: Based on what you've reported, they may be iron deficient. Please discuss this with their doctor, as this can have significant impact on their physical and mental health. If their doctor diagnoses iron deficiency, he or she will tell you the appropriate dose based on their weights. If it's not iron deficiency, the treatment would be different.

Maybe,maybe not: The levels needed to interfere with performance vary with the skill set being reviewed. Many with minor hemoglobin defects have lower values than the norm for their lifetime and function quite well.Lead poisoning can also cause lower values, but it is the lead, not the blood cells that cause impairments.In short, your statement provides nonspecific data so a more specific answer is not possible.