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.
Developmental Behavioral Pediatrician, Boston Childrenâs Hospital. Sometimes a developmental delay can be an early sign of learning issues. Sometimes it can be a sign of a genetic disorder or other medical condition. And sometimes a delay is just a delay. Some children eventually catch up and no longer have any developmental difficulties. This is one of the key differences between developmental delays and learning issues.