Among the nearly one-in-nine 14 and 15-year-olds who use their handheld device for at least four hours daily, grade scores suffer an average 14 percentage points across all subjects.
The deficit rises to more than 18 points in mathematics, figures from Japan's education ministry showed.
Nearly half of all third-year junior high school students questioned spend more than an hour a day on their phones, browsing websites, sending e-mails and playing games. Less than a quarter of those in the age group do not have a mobile.
Fifteen percent of them spend at least one hour on their device every day.
The results of the survey, which is the first of its kind by the education ministry, have sparked fears that schoolchildren are neglecting their books for the allure of the small screen.
Kazuo Takeuchi, who has studied the way youngsters use mobiles, told Jiji Press that children with the devices tend to lack confidence in their academic ability, and urged parents to set limits on their usage.
You’ve reached your limit of {{free_limit}} free articles this month.
Subscribe now for unlimited access.
Already subscribed? Log in
Subscribe to read the full story →
Smart Quarterly
₹900
3 Months
₹300/Month
Smart Essential
₹2,700
1 Year
₹225/Month
Super Saver
₹3,900
2 Years
₹162/Month
Renews automatically, cancel anytime
Here’s what’s included in our digital subscription plans
Exclusive premium stories online
Over 30 premium stories daily, handpicked by our editors


Complimentary Access to The New York Times
News, Games, Cooking, Audio, Wirecutter & The Athletic
Business Standard Epaper
Digital replica of our daily newspaper — with options to read, save, and share


Curated Newsletters
Insights on markets, finance, politics, tech, and more delivered to your inbox
Market Analysis & Investment Insights
In-depth market analysis & insights with access to The Smart Investor


Archives
Repository of articles and publications dating back to 1997
Ad-free Reading
Uninterrupted reading experience with no advertisements


Seamless Access Across All Devices
Access Business Standard across devices — mobile, tablet, or PC, via web or app
