Thanks to this Chicago blogger for finding and posting a summary of the testing schedule for the year ahead. Here's a sampling. Click the link for all the details.
K-2: DIBELS: September, January, May. (Schools not doing DIBELS must do either STEP or ISEL testing).
mClass Math (required): September, January, May.
Grades 3 - 8: Scantron (required for all schools, grades 3 - 8): September (the first three weeks after school starts); January; late April-May. Chicago Benchmark Assessment
(Reading/Math) (optional): October, January, May. Since this one is
optional, I don't know if my school will be taking it or not. Our Area
Office seems to like lots of data though, so... District Wide Writing Assessment (required): October, January, March 21-25, May. Note that the March test is used for promotion policy. ISAT (required): 2/28 - 3/11 (note it is a bit earlier next year).
Grade 8 only: EXPLORE: 9/27 - 10/6 Winter and Spring Benchmark and Scantron will overlap. The Winter Scantron testing is a month earlier than ISAT next year.