This study was designed to assess changes in low achievers' perceptions of classroom climate and junior high teachers' opinions of their teaching practices as a result of introducing a new set of mathematics curriculum materials. Nineteen teachers with two classes each participated. One class of each teacher used the new curriculum materials, Experiences in Mathematical Ideas (EMI), and the other class received the regular mathematics program for a period of six weeks. The Learning Environment Inventory for students and the Teacher Opinion of Practices Inventory were used as measurement instruments. Results showed that the students felt the EMI materials resulted in less confusion in class activities and goals, and the EMI materials did not change the opinions teachers had of their teaching practices. (Author/DT)