A 12 second loop with two day strips, one for Eastern Standard Time on top and one for UTC below, shifted 10 hours apart. A vertical now-line crosses both strips, and readouts show the local and UTC date and time. Local time sweeps from 0700 to 1200 on 21 May. While local time is before 1000, the UTC strip is still on 20 May. At 1000 local, UTC passes midnight and its date changes to 21 May. The sweep then returns to the lesson example, 21 May 0930 EST, which is 20 May 2330 UTC: subtract 10 hours, then check the date. A slider lets the learner set the local time directly. The still frame shows the 0930 example.
