Low Tech
Things like tactile sign language or finger spelling may be necessary to attempt to communicate with students who are both deaf and blind. If the students knows sign language, they can typically understand some of signs by placing their hands over the hands of whoever is signing. However, if the student does not know sign language, then this will be ineffective. Another low tech item that may be beneficial to students with deaf blindness is some type of manipulative. Manipulatives can help students feel objects that relate to what they are learning or they could use them to learn math concepts. Manipulatives alone will not teach students math concepts so they would have to be paired with some type of communication to portray a meaning. While using a manipulative may work with some students, they may be ineffective for others. Students may use them to play with instead of using them as a learning tool. They could be mistaken as a toy.
Mid Tech
These are braille keyboards that can be connected to a computer to type. The braille buttons will allow deaf blind students to recognize the letters and controls on the keyboard to type the message they want to convey. It may be difficult for them to connect the keyboard to the computer on their own especially if they aren't familiar with how to do it. It would also be difficult to correct any errors or even realize there are errors in their typing since they wouldn't be able to read it unless it is printed in braille for them to proof read.
High Tech
This is a type of computer that allows students to communicate with others. The keys are braille so that the students can understand what it is they are typing into the computer and then the computer has a text-to-speech setting in order to speak what the students type. If students have a moderate to severe hearing impairment, but are not deaf, there are volume controls and a headphone outlet where students can listen to what is being typed into the computer. If students don't understand braille then they will not be able to use this computer. If they make a mistake while typing, the message they are trying to share may not make sense to whoever is listening. Computers like this one can also be expensive.