Finding durations that cross hour boundaries or span multiple hours (e.g., 10:45 to 13:20), including counting on through noon/midnight.
Where your child meets this in real life: Working out journey times, shift lengths at work, or how long until an event
SEAGReady breaks calculate complex time durations into 3 steps, taught in order so each skill builds on the last.
Calculate duration when start and end times cross exactly one hour boundary (e.g., 10:45 to 11:20)
Calculate duration when start and end times span two or more complete hours (e.g., 10:45 to 13:20)
Calculate duration when times cross noon (am to pm) or midnight (pm to am), including in 24-hour format
Three free sample questions from our calculate complex time durations course. Every question comes with a full explanation, and hints that guide without giving the answer away.
Sean's football practice starts at 3:45 pm and finishes at 4:20 pm. How long is his football practice?
Answer: A. 35 minutes
Bridge through the hour: Step 1: From 3:45 to 4:00 = 15 minutes (60 - 45 = 15) Step 2: From 4:00 to 4:20 = 20 minutes Total: 15 + 20 = 35 minutes
Stuck? Start here: Start at 3:45. How many minutes until you reach 4:00?
Declan catches a train at 10:40 and arrives in Derry at 12:15. How long was his train journey?
Answer: A. 1 hour 35 minutes
Break it into chunks: Step 1: From 10:40 to 11:00 = 20 minutes Step 2: From 11:00 to 12:00 = 1 hour Step 3: From 12:00 to 12:15 = 15 minutes Total: 20 min + 1 hr + 15 min = 1 hour 35 minutes
Stuck? Start here: Start at 10:40. How many minutes until 11:00?
Niamh's family leaves Belfast at 11:45 am for a day trip. They arrive in Dublin at 2:10 pm. How long was their journey?
Answer: A. 2 hours 25 minutes
Use noon as a stepping stone: Step 1: From 11:45 am to 12:00 noon = 15 minutes Step 2: From 12:00 noon to 2:10 pm = 2 hours 10 minutes Total: 15 min + 2 hr 10 min = 2 hours 25 minutes
Stuck? Start here: Start at 11:45 am. Use 12:00 noon as a stepping stone
This is the exact interactive worked example your child sees in SEAGReady. Step through it and watch the method build up.
Aisling's swimming lesson starts at 10:45 and finishes at 11:20.
How long is her swimming lesson?
10:45 to 11:20
Step 1 of 4
Aisling's swimming lesson starts at 10:45 and finishes at 11:20.
How long is her swimming lesson?
Aisling's swimming lesson lasts 35 minutes.
The key insight: Bridge through the hour: count to :00, then add the rest!
Watch out: 11:20 − 10:45 = 0:75 = 75 minutes. You cannot subtract times like regular numbers. 20 − 45 gives a negative, which means you need to bridge through the hour.
These are the misconceptions we see most often in calculate complex time durations, including the ones our practice questions are specifically designed to catch.
Struggling with calculate complex time durations? The real gap is often in one of these earlier topics.
SEAGReady finds the exact step where your child gets stuck, teaches it with worked examples like the one above, and brings it back for review so it sticks.