Visualizing the 24-Hour Clock

To help students visualize how a 24-hour clock works and relates to a 12-hour clock, teacher Jo Leland of Kingwood, TX, suggests using a clock face with two parts -- an inner ring with hours 1-12 and an outer ring with hours 13-24. To help students calcualte the minutes of a photoperiod she suggests having an actual clock with moveable hands.

Jo Leland
Hidden Hollow Elementary
Kingwood, TX
jo.leland@humble.k12.tx.us

I've always wanted to make a clock face with two parts. Front would be white and have the regular clock hours, but on a larger outer circle of the clock face there would be a different color circle with the second half of the numbers that make up 24-hour or military time. For most of our kids, understanding 24-hour time can be a very difficult task.

I find that for most kids, the concept of military time is both easy and confusing. Especially as the numbering actually crosses over in both directions at noon and midnight.

 This two-part clock in the photo is my idea to simplify matching 24-hour time to the a.m. and p.m. Click on clock for full size image Be sure to include the arrows shown if you make one for yourself.

An added suggestion for students to use in calculating the minutes aspect of photoperiod is to find or make a clock with actual moveable hands. For kids that have a hard time with calculating the minutes par , a clock with moveable hands may be helpful. I've had some luck with one of those little manipulative clocks by Little Judy? They are yellow.

My approach is to first have the students count the number of whole hours from sunrise time, to the point where all that remains is a partial hour. After calculating the whole hours, we then count the remaining minutes in the partial hour in chunks, until sunset time. By "in chunks" , I mean take it in steps. For example, first we count the number of minutes to the next next 5 minute mark on the clock, then count the number of minutes to next :30 or :00 point, and so on. Once we have counted the number of minutes to sunset in this las partial hour, then we add the minutes to the number of whole hours counted. Turning the hands seems to help for counting the minutes....

If you have tips you'd like to share, please write to Journey North: jnorth@learner.org