Lesson observations: Approach with caution!
For any measure of teaching effectiveness to be useful, it needs to be valid. To be valid, a measure also needs to be reliable. Reliability represents the consistency of a measure. A measure is said to have a high reliability if it produces similar results each time – for example if two observers independently rate the same lesson, those ratings should agree with one another. Validity represents the extent to which a measurement corresponds to what it aimed to measure. So a valid observation would measure genuine learning gains, rather than be subject to bias.
We’ve known for some time that classroom observations lack the reliability for high-stakes judgements of teacher effectiveness. For example, the MET project – which spent millions of dollars spent to produce robust observation protocols – found that even for these carefully constructed observation measures, the reported reliabilities of observation instruments…
View original post 1,379 more words