Murray,
From my training in Computer Science, I am well aware of the "assignment" equal sign such as FORTRAN's
X = X + 1. ALGOL "solved" the problem by introducing another symbol, " := ". C kept " = " as assignment,
but substituted " == " for comparison.
But the "assignment = " is also the "equal" sign on the pocket calculator, so
7 + 3 = 10 + 3 = 13 − 8 = 5
is exactly the way you would do the problem on a calculator.
Another related but sometimes overlooked convention is that subtraction is left-associative.
10 - 5 - 2 = ( (10 - 5) - 2) = 3 not (10 - (5 - 2) ) = 7
But to my original point, these are pitfalls we learn to handle in "real" algebra.
But I'm wondering whether the 4th grader is being taught algebra,
or is just being confused by being shown an algebraic-style notation that the student doesn't really understand.
I believe true algebraic thinking is the key to solving word problems.
But I'm not convinced that my 4th grade student is actually learning "algebraic thinking".
I suppose I could go further, and ask whether it is appropriate to introduce "word problems" without teaching the tools and procedures to solve them properly.