Products that contain bismuth can temporarily turn your tongue black, according to Atlas of Adult Physical Diagnosis. Other Causes If you have a black tongue, then you could have a fungus called Aspergillus niger growing on the surface of your tongue. If you have too much bacteria growing in your mouth, it could cause your tongue to appear black and hairy, according to the Mayo Clinic.
In addition, a child is said to have a cognitive delay and/or a learning disability when they are performing at least two grade levels below their peers. For example, a third grade class is learning their multiplication tables, but a student with a cognitive delay would be performing math on a first grade level.
Learner's definition of HABIT. 1. : a usual way of behaving : something that a person does often in a regular and repeated way. [count] It was his habit to take a nap after dinner every evening. It's important that parents teach their children good study/eating habits.