You are correct in saying it’s too much to present all forms of the simple past in one lesson. You’re also right to focus on simple past questions and short answers.
Target language is simply the language you aim to present in a lesson. This is in contrast to language that is explained or taught because a student asks a question about it – the teacher didn’t plan to cover this.
The language you have chosen to focus on can be described as:
Simple past closed questions i.e. did + subject + verb in base form
Short answers i.e. yes + subject + did or no + subject + didn’t
You also need to decide whether to focus on the past of the verb “to be”. If so, include:
“To be”: simple past closed questions i.e. was / were + subject
“To be” short answers i.e. yes + subject + was / were or no + subject + wasn’t / weren’t.
I guess that if you are concerned about the wording of your target language, your plan is going to be evaluated. If this is the case, you might like to check with this person exactly what they are looking for.