Modeling
Children must learn to model word problems. While there are other ways
to solve word problems (that is, by using shortcuts) children cannot
understand those
other ways without the ability to make models.
Of course it is obvious that children are not born with the
ability to make models. In this
example
it is clear that Trixie does
not know how to model the problem  she simply doesn't
understand the question
and so she has no way to solve it. One way or another Trixie
must learn what to do  the question is, "How is she to do
that?"
I believe that modeling should be explicitly taught. The 12
types of word problems should be systematically
introduced and children should be provided with clear direction on how
the problems are to be
solved.
Here is some general advice on teaching your child to model word problems.

 Although I do believe in systematically introducing all 12 types
of problems,
I don't believe in teaching only one type at a time. Mix the problems
up. For
example, your child need not be expert with Easy Addition before being
introduced to Easy Subtraction.
 Keep the numbers small  under 10 to begin with and always under
20.
Larger numbers just make the counting tedious and error prone  and
contribute nothing to learning to model.
 Remember, you are teaching your child to model. It is the modeling process that is important  not speed or even the right answer.