This Math Problem for 8-Year-Olds Left Parents Stumped

iStock
iStock

Life for grade-schoolers has changed a lot in just a few decades. While students growing up in the pre-digital age had to suffer through insanely difficult homework in silence, kids (and their parents) today can share their frustrations on the internet.

According to Over Sixty, the latest assignment to go viral comes from the parenting message board Mumsnet. After posting their 8-year-old child's math homework on a forum, user lucysmam quickly saw that the other parents were just as baffled by it. Here's the problem:

“On the coast there are three lighthouses. The first light shines for 3 seconds, then it is off for 3 seconds. The second light shines for 4 seconds, then it is off for 4 seconds. The third light shines for 5 seconds, then it is off for 5 seconds. All three lights have just come on together.

When is the first time that all three of the lights will be off together?

When is the next time that all three lights will come on at exactly the same moment?”

Give up? The answer the parents came up with was 6 seconds for the first question and 120 seconds for the second one. The question becomes easier when you think of the lighthouses this way: The first one lights up every 6 seconds, the second one lights up every 8 seconds, and the third one lights up every 10 seconds. To calculate when all the lights will coincide, you need to find the lowest number divisible by six, eight, and 10, which comes out to 120.

When it comes to head-scratching elementary school lessons, this problem is just the start. If this viral problem is any indication, 6-year-olds have it even worse than 8-year-olds.

[h/t Over Sixty]

This Course Will Teach You How to Play Guitar Like a Pro for $29

BartekSzewczyk/iStock via Getty Images
BartekSzewczyk/iStock via Getty Images

Be honest: You’ve watched a YouTube video or two in an attempt to learn how to play a song on the guitar. Whether it was through tabs or simply copying whatever you saw on the screen, the fun always ends when friends start throwing out requests for songs you have no idea how to play. So how about you actually learn how to play guitar for real this time?

It’s now possible to learn guitar from home with the Ultimate Beginner to Expert Guitar Lessons Bundle, which is currently on sale for $29. Grab that Gibson, Fender, or whatever you have handy, and learn to strum rhythms from scratch.

The strumming course will teach you how to count beats and rests to turn your hands and fingers into the perfect accompaniment for your own voice or other musicians. Then, you can take things a step further and learn advanced jamming and soloing to riff anytime, anywhere. This course will teach you to improvise across various chords and progressions so you can jump into any jam with something original. You’ll also have the chance to dive deep into the major guitar genres of bluegrass, blues, and jazz. Lessons in jam etiquette, genre history, and how to read music will separate you from a novice player.

This bundle also includes courses in ear training so you can properly identify any relative note, interval, or pitch. That way, you can play along with any song when it comes on, or even understand how to modify it into the key you’d prefer. And when the time comes to perform, be prepared with skilled hammer-ons, pull-offs, slides, bends, trills, vibrato, and fret-tapping. Not only will you learn the basic foundations of guitar, you’ll ultimately be able to develop your own style with the help of these lessons.

The Ultimate Beginner to Expert Guitar Lessons Bundle is discounted for a limited time. Act on this $29 offer now to work on those fingertip calluses and play like a pro.

 

The Ultimate Beginner to Expert Guitar Lessons Bundle - $29

See Deal


At Mental Floss, we only write about the products we love and want to share with our readers, so all products are chosen independently by our editors. Mental Floss has affiliate relationships with certain retailers and may receive a percentage of any sale made from the links on this page. Prices and availability are accurate as of the time of publication.

How the Trapper Keeper Trapped the Hearts of '80s and '90s Kids

Courtesy of Cinzia Reale-Castello
Courtesy of Cinzia Reale-Castello

No matter when or where you grew up, back-to-school shopping typically revolved around two things: clothing and school supplies. And if you’re an adult of a certain age, you probably had a Trapper Keeper on that latter list of must-buy items.

Like the stickers, skins, and cases that adorn your smartphones and laptops today, Trapper Keepers were a way for kids to express their individual personalities. The three-ring binders dominated classrooms in the '80s and '90s, and featured a vast array of designs—from colorful Lisa Frank illustrations to photos of cool cars and popular celebrities—that allowed kids to customize their organizational tools. 

In this episode of "Throwback," we're ripping open the Velcro cover and digging into the history of the Trapper Keeper. You can watch the full episode below.

Be sure to head here and subscribe so you don't miss an episode of "Throwback," where we explore the fascinating stories behind some of the greatest toys and trends from your childhood.