So, as you might know, I will be teaching writing to 3rd and 4th graders in the summer (going on to 4th and 5th grade). Some 3rd and 4th graders will be more proficient than others as far as their writing goes. That's probably true of all other subjects as well. In any case, Because different students have different needs, I must figure out exactly what their needs are. After I figure out what their needs are, then I can better decide what skills they need to focus on.
Something I had considered was just a practice CA STAR test on writing conventions, vocabulary, and spelling errors. At the beginning of the 2011-12 school year, my complaint about multiple choice tests in general is that if a student bubbles in the right answer, you don't know whether they actually knew what the right answer was or whether they were just guessing. That's still my complaint today, but I've realized there are still some benefits to a multiple choice test.
#1 They're fast. Students just read a sentence from their test booklet and mark what they think the correct answer. What is this fast compared to? It's fast compared to having students write something in response to a prompt and then reviewing it for grammar, spelling, vocabulary, cohesion, clarity, and so on.
#2 It tells you what students don't know. Here's the deal. If a student knows what the correct answer is and they want to get the correct answer, then they will mark it. You still don't necessarily know whether they know, but that doesn't change that if they do indeed know what the correct answer is, then they'll bubble it in. However, when a student bubbles in an answer which is incorrect, then you know what they don't know.
Having said that, I will stick to looking at student writing samples. The only reason why is because a single sample of their writing will give me way more examples of their strengths and weaknesses than mere multiple choice questions.