On Evaluating Speaking Skills
It can be quite challenging to evaluate spoken language ability with foreign-language learners.
I believe that although it has some faults, the style and rubrics of the iBT (internet-based TOEFL) are actually fairly effective, but they are too formal for elementary-age students.
While at my last hagwon job, I designed and shared with my coworkers a set of speaking-evaluation rubrics to help standardize scores between different classes and levels.
I have posted a sample of these rubrics.
One other evaluation technique that I applied very successfully in my Spanish-as-a-Foreign-Language classroom back in the 1990's was what I came to think of as the "graded interview" technique.
The idea is to have a series of increasingly more difficult "topic cards" which contain some kind of question or "role-play" request, which should take no more than a minute or two to complete.
The teacher draws a card from the simplest pile, and if the student does well with that card, the teacher moves to the next, more difficult pile of cards. Increasingly more difficult cards are presented, until the student fails to do well. This is then taken to be the student's level of ability. This is both repeatable and not level-specific, so that a single test can be used both for placement and to evaluate progress.
Ultimately, however, in a "fun" and well-managed elementary language-learning classroom, each student's ongoing effort is the primary basis for evaluation. Teachers should make an effort to know their students, and to be familiar their strengths and weakness and interests.