Seconds, minutes and hours

You know that sixty minutes make one hour. Today, we will change between seconds and minutes. A stopwatch shows one hundred and sixty-seven seconds for a walk round the estate. How many minutes and seconds is that? Here is the stopwatch, showing one hundred and sixty-seven seconds. First, we draw the walk as a strip, one hundred and sixty-seven seconds long. To find the minutes, we watch the walk again from zero. Watch the red second hand go once around. The stopwatch now shows sixty seconds. The purple minute hand has moved on one mark. So one minute is sixty seconds. On the strip, the first sixty seconds fill one block. The walk is longer than one minute, so we let the stopwatch run on. The red hand went around one more time, so a second block of sixty seconds fills. Then the red hand stopped before it got back to the top. So the end of the walk is less than one minute. A third block of sixty seconds would not fit. So the walk has two whole minutes. There are two full blocks, so we add their seconds. Sixty seconds plus sixty seconds is one hundred and twenty seconds. Now, how many seconds are left after the two minutes? To find the seconds that are left, we subtract. One hundred and sixty-seven minus one hundred and twenty is forty-seven. So the last block is forty-seven seconds. One hundred and twenty seconds is two minutes. So the walk took two minutes forty-seven seconds. A chime lasts two minutes thirty-eight seconds. Express this duration in seconds. Try it first. Pause if you like. Watch the chime on a clock, from zero. Each minute is sixty seconds, so the two minutes are two blocks of sixty seconds. Then come the thirty-eight seconds. To find the seconds in two minutes, we multiply sixty by two. Sixty times two is one hundred and twenty. The chime is the two minutes and the thirty-eight seconds, so we add. One hundred and twenty plus thirty-eight is one hundred and fifty-eight.

Add nine minutes thirty-nine seconds and forty-six seconds. Give your answer in minutes and seconds. Try it first. Pause if you like. Seconds go with seconds, so we add the seconds first. Here are the thirty-nine seconds. And here are the forty-six seconds. Thirty-nine plus forty-six is eighty-five. Eighty-five seconds is more than sixty seconds, so we mark sixty seconds on the strip. To find the seconds after the mark, we subtract sixty. Eighty-five minus sixty is twenty-five. So eighty-five seconds is sixty seconds and twenty-five seconds. Sixty seconds make one minute, so eighty-five seconds is one minute twenty-five seconds. This sixty-second part makes one extra minute, which we add to the nine minutes. Nine minutes plus one minute twenty-five seconds is ten minutes twenty-five seconds. Check on a clock, starting at nine minutes thirty-nine seconds and adding forty-six seconds. Sixty seconds make one minute.