30 Minutes in the Bath Turned Into 90? The “24-Hour Dial” Reveals Where Your Summer Time Really Goes
I’m Science Trainer Ken Kuwako. Every day is an experiment.
“Have you ever planned to soak in the bath for just 30 minutes, only to realize an hour and a half has flown by?” Most of us have. The time we feel passing and the time actually ticking away are often surprisingly different.
As summer vacation approaches, seeing my students buzzing with excitement reminds me of my own school holidays. But long breaks also make it easy to fall into irregular routines. I wanted my students to make the most of this precious time, so this year I introduced a slightly different activity in class.
The idea came from a blog post written by one of my senior colleagues. It introduced a method called the “24-Hour Dial,” a circular planner that helps you design your day visually.
The concept is simple: first fill in the hours that can’t be changed—sleep, commuting, school, and so on. Then decide how you want to use the remaining hours. The article even suggested simulating what happens when your schedule gets disrupted. As soon as I read it, I thought, “This would be perfect for planning summer vacation.”
Making Time Visible with the “24-Hour Dial”
I handed out copies of the 24-Hour Dial and asked my students to design their ideal summer vacation day.
I suggested they fill it out in this order:
・Start with the “non-negotiable” parts of the day, such as sleep, meals, and club activities.
・Next, reserve time for things that shouldn’t be skipped, like homework and spending time with family.
One thing that surprised many students was discovering their “hidden hours”—the time that quietly disappears without them noticing.
The example from my colleague’s blog hit home: “You think you’re only taking a 30-minute bath, but you bring your phone with you, and before you know it, 90 minutes have passed.” It turns out adults aren’t the only ones who experience this.
Thirty minutes of gaming every day. An hour scrolling through social media. These small chunks of time are easy to overlook until they’re written down on the dial, where they suddenly become impossible to ignore.
Why Do Hidden Hours Appear?
This gap between perceived time and actual time is a well-studied topic in psychology and neuroscience.
When we’re deeply engaged with activities that constantly provide new stimulation—like smartphones or video games—our brains continue releasing dopamine. As a result, the brain’s internal sense of time becomes less accurate, creating that familiar feeling of completely losing track of time.
There’s also a famous idea known as Parkinson’s Law: “Work expands to fill the time available for its completion.”
Homework is a perfect example. If students believe they have plenty of time before the deadline, the task often stretches far longer than it actually needs to.
Creating a pie-chart-like visualization of an entire day with the 24-Hour Dial helps students work against these natural mental habits. It encourages them to step back and look objectively at how they spend their time.
I filled one out myself as well. It made me realize how much time everyday chores take—and that I still have opportunities to help more around the house. Here’s what one of my summer vacation days looks like. Teachers don’t actually get the whole summer off, but the schedule is definitely less demanding than during the school term, so I’m looking forward to it.
What My Students Discovered
The activity led to many interesting reflections.
“I realized I have much less free time than I thought.”
“I can’t believe I spend this much time on my phone…”
“I feel like making a plan will actually help me do more of the things I want.”
One student even commented, “Things probably won’t always go according to plan, but I still think it’s worth trying.”
That optimistic attitude—thinking “What if I try this?” instead of “There’s no point anyway”—was exactly what I had hoped to see.
This wasn’t just about creating a summer schedule. It was a first step toward helping students become more aware of how they spend their time and develop better self-management skills.
I’m already looking forward to hearing, after summer vacation, how closely they followed their plans and what unexpected discoveries they made along the way.
Interestingly, the very idea of dividing a day with a circle has ancient roots.
The Babylonians developed the concept of dividing a circle into 360 degrees, and that way of thinking eventually influenced both our measurement of angles and the design of sundials. For thousands of years, people have transformed the movement of the Sun into a circular visual representation to better understand the passage of time.
The 24-Hour Dial is simply a modern version of that timeless idea—a tool that helps us make time visible.
I hope this activity helps my students spend a summer that’s organized, meaningful, and uniquely their own.
If you’re interested, you can also download a daily schedule worksheet from the Happy Lilac website.
With summer vacation just around the corner, a simple visual planner like this can make it much easier to build a balanced routine at your own pace. I’m thinking of having my own children try it as well.
In another article, I also recommend creating a point card or a stamp sheet to help build good habits.
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