From a young age we all grow to fear our parents uttering those soul-crushing words - "I'm not angry. I'm just disappointed". Our parents could shout at us for hours on end and nothing would compare to the intolerable, sick-to-the-stomach feeling of knowing that they are disappointed in us. Even as an adult, we dread hearing those words.
This means that small tensions can easily escalate and in school this takes away from precious teaching time. The impact this has on their longer term attainment is that they may be unable to meet their full potential and can at times hold back other pupils in the class with the distractions they create.