Manually Coded English is basically a system of English codes on the hands, using some ASL signs and adapting ASL signs. Uses English word order and grammar paralleled to English.
MCE is a category of S.E.E 1 (Seeing Essential English), S.E.E. (Signing Exact English). They emerged in the 1970s after realizing the failure of oralism during the "Dark Age" between the infamous Milan of Congress of 1880 and the 1960s.
At around the same time, in the 1960s, Dr. William Stokoe of Gallaudet Unviversity discovered the linguistics of American Sign Language.
Signing Exact English is a manually coded form of English. It's not a natural language.
S.E.E. and other MCEs corrupted language acquisiton and education. This is an analog to forcing children to write English (grammar) using spoken/written words of a language (French, Arabic, or any). In the end, these children often struggled.
"It goes to-me good." What? It's a transcription for the German phrase, "Es geht mir gut." which means "I'm doing fine" in English. English and German have their own structure. Same for ASL that cannot be Englishized.
In the 1980s, ASL courses flourished across North America. But, signed communication becomes widespread in the U.S. classrooms, not ASL. Total Communication (TC) and Simultaneous Communication (simcom) were developed in classrooms.
In the 1990s, a study presents 90% of teachers of the Deaf used TC. And, 80% of teachers of the programs for Deaf children used an MCE system.
The results in these decades show that education for Deaf children has not improved. Deaf children of Deaf parents often outperformed deaf children of non-signing hearing parents in language acquisition, literacy, education, leadership, and so on.
Nativization hypothesis is that all children have an innate mechanism for the acquisition of language through language experience. MCE can disrupt nativization of language learning. It inhibits or limits the development of language especially a second language, English. With a strong full-fledged language acquisition in ASL from birth, children have no problem learning English.
Linguistics and neuroscience research and studies recognize that ASL is a natural, real language. Bilingualism is clearly the best approach to education of the Deaf. Today it's a norm in many Deaf schools. Through bilingualism (ASL and English) in education, Deaf students attain education and literacy on par with hearing students.
Related signs: simultaneous communication.