Though there is no single, thoroughly researched and widely practiced âmodelâ of the RTI process, it is generally defined as a three-tier (or three-step) model of school supports that uses research-based academic and/or behavioral interventions.The Three-Tier Model is described below.hough there is no single, thoroughly researched and widely practiced âmodelâ of the RTI process, it is generally defined as a three-tier (or three-step) model of school supports that uses research-based academic and/or behavioral interventions. The Three-Tier Model is described below.
Franklin Delano Roosevelt is the US President who served the greatest number of years in office. He was President from 1933 to 1945, which was 12 years. Currently, Preside â¦ nts are constitutionally limited to two consecutive terms, adding up to only 8 years.
Which US President served for the longest term? Franklin D. Roosevelt (32nd President) served for  12 years and 1 month, from March 4, 1933 until his death in office  on April 12, 1945. FDR was elected four times, and theâ¦ remaining 39  months of his 4th term were served by his new Vice President, Harry  Truman.