This means the first lesson of the day.
A foot ball game has two halves. So, I know is that the translation for the "First half" is "Kipindi cha kwanza"
It is first period ( usualy half of the school year) First lesson should to be - somo la kwanza.
Not necessarily. Kipindi is a period of time, so I guess this could be the first period of the day, or it could be the first term, depending on that magical thing called context that this course so often lacks.
If the first half of the school year is meant, the English should say first semester or first term, not first period (=first lesson of the day).
There is a lot of inconsistency with regard to the use of the article in the English sentences given as correct answers.