Developing an IEP requires an understanding of a child's current strengths and weaknesses, and a description of "present levels of performance" is part of the required content for an IEP document. However, defining what that means in a practical sense can be difficult."Baseline data" is a way of referring to the where the child is performing on a specific skill at that time. It is a "starting place" based (hopefully) on concrete, understandable information derived from measurements of the child's performance in that area. Understanding, and including, the baseline can give the IEP team the ability to write clear, measureable goals that will allow the child to make real progress.
Baseline data can be taken from a variety of places. For example, if a child's prior IEP included a goal in a specific area, the data collected from the measurement of that goal can give you a baseline for that same skill going forward. Baseline data could also come from standardized tests, classroom based assessments, or statewide / schoolwide testing results.
Here are some examples:If the IEP team wants to write a goal for reading fluency, you would need to know what the child's current achievement is in this area in order to write a goal that will allow for progress going forward. Reading fluency could be measured in accurate words per minute (wpm) or by the score from a standardized fluency test. That becomes the baseline by which progress towards the goal can be set.
If the child needs a goal in the area of behavior, specifically to address on task behavior or work completion, data can be taken in the classroom setting to establish baseline data.