Skip to content
Made ForHomeschool

Skills / Ages 8 to 11 / Math

Read seconds on a clock

Reading a timer or stopwatch that shows minutes and seconds with a colon between them, and turning that reading into plain seconds, so 2:40 becomes 160 seconds.

Why it matters

Timers on phones and ovens show minutes and seconds, but a science notebook writes every time in plain seconds so the numbers can be lined up and compared. A child who reads 1:25 as 85 seconds, and never as 1.25, can compare any two timings.

What it looks like when your child can do it

  • Shown 1:20 on a phone timer, your child says one minute and twenty seconds, which is 80 seconds.
  • Your child reads the number before the colon as minutes and the number after it as seconds, every time.
  • Your child watches the second hand on a wall clock and can tell when ten seconds have gone by.

How to teach it at the kitchen table

  1. 01

    Watch a minute go by

    Start a timer and watch the seconds count up to 0:59 and roll over to 1:00. Say it out loud: sixty seconds make one minute. Seeing the rollover makes the rule stick.

  2. 02

    Name the two sides of the colon

    Before the colon is minutes. After the colon is seconds. Point to each side and say the word, then have your child do the same on a few readings.

  3. 03

    Turn minutes into seconds

    Each minute is 60 seconds. Multiply the minutes by 60, then add the seconds after the colon. 2:40 is 120 plus 40, which is 160 seconds.

  4. 04

    Say what the reading is not

    1:35 is not one point three five, and it is not one hundred thirty-five. It is one minute and thirty-five seconds, which is 95 seconds. Say the wrong readings out loud so your child hears why they are wrong.

You will need: A phone or kitchen timer · A clock with a second hand, if you have one · Paper and a pencil

Try it together

  1. Try 1

    Write 0:38. Ask how many seconds that is.

    Listen for  38 seconds. There are no whole minutes, so the seconds are the whole answer.

  2. Try 2

    Write 1:50. Ask for plain seconds.

    Listen for  110 seconds, because 60 plus 50 is 110.

  3. Try 3

    Write 2:15. Ask for plain seconds.

    Listen for  135 seconds. Two minutes is 120 seconds, and 120 plus 15 is 135.

  4. Try 4

    Write 1:35 and ask whether it means one point three five.

    Listen for  No. It means one minute and thirty-five seconds, which is 95 seconds. Listen for the reason: a colon is not a decimal point.

  5. Try 5

    Write 3:05. Ask for plain seconds.

    Listen for  185 seconds. Three minutes is 180 seconds, plus 5. Watch that the 05 does not turn into 50.

Watch for

  • Reading 3:05 as 3 minutes and 50 seconds. The 0 matters: 05 is five seconds.
  • Many stopwatches also show a point after the seconds, like 0:07.4. The part after the point is tenths of a second, a real decimal, and it is a different thing from the colon.

If it is not there yet

  • Stay with readings under two minutes, like 1:10 and 1:40, until adding 60 comes without effort.
  • Count seconds out loud with a timer running and stop together at 1:00, so the rollover is seen and not only told.

A few days of this is normal, and it is time well spent. The lesson will still be there, and it will go faster.

Where this skill comes up

  • How Scientists Actually Find Out · Lesson 8

    Timing It

    Needs it because the sheet reads several stopwatch faces and converts them before any timing happens.