transforming a statement

what has happened?

describe each of the steps

intuitive knowledge about rearrangement can be obtained from simple number sentences and their equivalent forms, relating the transformation to e.g. subtract 4 because it's the inverse of add 4  e.g. divide by 3 because it's the inverse of multiply by 3 

objectivity can be established over time - by participating in discussion

my preference is to enable students to develop their own notions about rearrangements by presenting them with examples - including what happens in more demanding cases