4 Types of Immersion Programs

Full Immersion
Typically begins in Kindergarten with monolingual students.  The school day is entirely in the target language for the first few years. Reading and writing are initially taught in the target language.  The percentage of the target language spoken in a classroom decreases as the student ages.  By middle school the student only spends half of the day in the target language.
Partial Immersion
In partial immersion the day is divided into native language and target language sections, generally a 50/50 division.  Reading and writing is taught both in the native language as well as in the target language.  The ratio of target language to native language used in the classroom remains consistent throughout each grade.
Double Immersion
This program uses the full immersion method to teach two different languages.  For example in Canada there is a French-Hebrew school that is attended by mostly English speakers.  Reading and writing is taught initially in the non-native languages.  As students move up in grade level, they will begin to have more English classes.
Dual Immersion
This type of immersion was developed in Florida.  The program takes students who know only one language, for example English, and mixes them with students who know only a different language, for example Spanish.  The goal is that both groups of students will become fluent in both languages.  The students work together to teach each other what they know about their own language.