Time is a popular subject in both Junior High and elementary school.
Here are a few games and activities which could come in useful for this topic.
1) Line / row game
Students stand in lines and rows (usually their seating plan works fine).
Hold up a clock and ask 'what time is it now'.
The first student to raise their hand answers, if correct they choose either their line, or row, to sit down.
Repeat using different times until only one student is standing.
If you are short for time, end it here.
If you want to continue get the line, or row, including that student to stand back up.
Continue as long as you wish.
2) Timed game
Give all students a slip of paper with a time written on it. (either a clock or digital depending on the age/ability of your students).
Set a timer for 2 or 3 minutes.
In pairs students ask each other "What time is it now" and answer.
They take a note of the friends name, and time, and repeat until the time runs out.
The student who asked the most people, is the winner.
3) Whisper game
Students sit in lines (again, their seating plan usually works fine).
The first student should be given a a clock or something to write the answer on.
The students at the back of the line gets told a time (I usually take them outside so I can get them to repeat the time back to me to check their understanding).
They then whisper it to the student in front of them, and so on.
The student sitting at the front of the line come to you with the answer.
The first team with the correct answer gets 5 points, second team 4 points etc.
N.B. It is definitely worth making some clocks. I made 6 clocks, and although it can take a lot of time it is worth it in the long run.