Student Growth Portfolios for Teacher Evaluation
February 2020
Authors: Anna Johnson, Juan Napoles, and Linda Wesson
The Comptroller’s Office was asked to evaluate the use of portfolios in Tennessee’s teacher evaluation system. Portfolios contain collections of student work, selected by teachers, from two points in time during the school year to show students’ progress in mastering specified state academic standards. Portfolio scores are incorporated into teachers’ overall
annual evaluations. The state requires local school districts to use portfolios for some teachers: primarily pre-k and kindergarten teachers in districts that receive state funding for Voluntary Pre-kindergarten classrooms.
Portfolio scores serve as an alternative to the student growth portion of teacher evaluations for teachers whose students do not take a statewide standardized test (TN Ready) and, thus, the teachers do not receive individual Tennessee Value-Added Assessment System (TVAAS) scores. Teachers without an individual TVAAS score, and whose district has not selected a portfolio model in their grade or subject, receive a school-level TVAAS score.
The evaluation found that several factors in the design of portfolio models weaken their validity and reliability as a quantitative measure of student growth. Also, teachers with portfolios were considerably more likely to receive the top score for the student growth component of their evaluations than teachers with individual or school-level TVAAS scores. In
2018-19, 74 percent of portfolio teachers received the top growth score of 5, compared to 19 percent of teachers with individual TVAAS scores and 34 percent of teachers with school-level TVAAS scores. Tennessee appears to be the only state
using portfolios as a student growth measure for teacher evaluation purposes.
The report includes several policy considerations for both the General Assembly and the Tennessee Department of Education, including methods to increase the validity and reliability of portfolio models and options to shift the primary use of portfolios from a measure of student growth to a professional development tool to improve teachers’ instructional practice.