Assessments help me get to know your child as a learner. They help the learning team begin to put together the pieces, and understand which pieces are missing. One assessment, one piece of student work, one teacher anecdote, one quiz are examples of snapshot assessments that give us a peak into how a student is progressing. 
 
But real student growth should be evaluated in myriad ways and include snapshots over time. With enough data over time, we begin to see a photo album. A snapshot shows a child in one moment. A photo album shows the child on many days in many different ways over a period of time.