What is the  difference between accommodations & modifications?
http://www.healthcentral.com/adhd/c/1443/36739/accommodations

What is an Educational Assessment Accommodation?

Accommodations are practices and procedures that fall into four major areas:

  1. Timing/Scheduling
  2. Setting
  3. Presentation
  4. Response
  • Accommodations are intended to increase access to grade level content for students who are potentially most impacted by conditions which interfere with them demonstrating their knowledge.
  • Accommodations provided to a student during state assessments should be similar to those provided during classroom instruction and classroom assessments. However, some instructional accommodations are not appropriate for use on state assessments. It’s important for educators to become familiar with state recommendations regarding the appropriate use of accommodations during assessments to ensure they are administered appropriately.
  • Accommodations for students with disabilities are intended to help students demonstrate their knowledge of test content without altering the test construct, what the test is truly intended to measure.
  • Accommodations for students with disabilities involve changes to testing materials, testing procedures, and/or the testing situation to allow the student to participate meaningfully in an assessment.
  • Accommodations for students with disabilities provide results that are comparable to standard (i.e. accommodated) assessments

(ASES)Assessing Special Education Students: Accommodations Manual
How to Select Administer and Evaluate Accommodations for Instruction and Assessment of Students with Disabilities

(CCSSO) Council of Chief  State School Officers: Accommodations FACTS Sheets & Teacher Tools

ISBE  2011 State Approved Tesing Accomodations for IEP/504/LEP:GRID

ISBE  2011 Accommodations Guidance