# Tommi Roininen

## 27 Added | 6 Magazines | @TommiRoininen | ICT and maths teacher in Pikkolan koulu, Finland

### Prosenttilasku saa monen aivot solmuun – Opettajat: Kiire pois matikantunnilta

Prosenttilaskun vaikeus johtuu siitä, että koko prosentin käsite on jäänyt monelle ihmiselle hämäräksi. Näin arvioi Matemaattisten aineiden …

### Archimedes’ principle

<b>Background of Archimedes</b><p>Archimedes was born in 287 BC into a wealthy family of nobility and his hometown was a small village near to Greece. He also …

Mathematics### Is Math an Invention or a Discovery?

<b>Who knew that an unlikely friendship and a few games of cricket with one of the greatest mathematicians in the early 20th Century could lead to a</b> …

### Einstein's election riddle: are you in the two per cent that can solve it?

Nicola lives in the tartan house, but who owns the fish?<p>Stumped? Here’s how to solve Einstein’s election riddle<p>Last month I blogged about a logic puzzle that had gone viral in Singapore. My posts on Cheryl’s birthday problem attracted more readers than anything I have ever written before: more than …

Mathematics### What would you see in a black hole?

What would it be like to fly a spacecraft into a black hole? Marcus Woo investigates.<p>Something about a black hole just pulls you in. Sure, its gravity is so strong that not even light can elude its grasp. But, there's something else, something harder to pinpoint. Maybe it's a black hole's absolute …

Black Holes### Use Orion’s Belt to find Mercury

Mercury’s greatest eastern elongation – its greatest distance from the sunset – is today. But how can you tell which object you’re seeing is …

Astronomy### Amazon Goes After Dropbox, Google, Microsoft With Unlimited Cloud Drive Storage

Last year, Amazon gave a boost to its Prime members when it launched a free, unlimited photo storage for them on Cloud Drive. Today, the company is expanding that service as a paid offering to cover other kinds of content, and to users outside of its loyalty program. Unlimited Cloud Storage will …

Cloud Computing### iOS Game Mr Jump Leaps To 5M Downloads After Four Days On The App Store

This weekend I jumped a lot, and more than a few of these jumps ended in death: I was playing Mr Jump, a new iPhone and iPad game that rewards pattern identification and memorization like the best of the old-school platformers. The game from France’s 1Button has already racked up 5 million …

App Store### What The Apple Watch Could Be

What is the Apple Watch? The simple answer is Apple’s first smartwatch. In fact Apple calls it its “most personal device ever”. But early reviewers have wrestled with the <i>raison d’être</i> of the Apple Watch.<p>“Do you want another tiny computer in your life that you have to worry about and charge every …

Smartwatches### Google Launches Its Own Wireless Service, Project Fi

As rumored for months, Google has just announced plans to offer its own wireless cellular service.<p><b>Here’s what we know so far:</b><p>It’s called “Project Fi”<br>• It’s for Nexus 6 owners only, at first.<br>• It’s invite only right now. You can sign up for an invite here.<br>• It’s built on top of Sprint and T-Mobile’s …

Telecoms### WhatsApp Begins Rolling Out Its Voice-Calling Feature To iOS Users

Less than a month after WhatsApp introduced free voice calls to users of its Android app, so the Facebook-owned company has begun rolling the feature out to its iOS customers.<p>Like the launch of calling on Android, which was first spotted by eager users in February, the feature will not be available …

Apps### Astronaut food: Can you cook fries in space?

Think reaching Mars is a challenge, how about cooking a decent meal on the way? Enter the weird science of cooking in space, starting with the humble chip.<p>If humans ever voyage to a planet far bigger than Earth, the journey is sure to be arduous and full of danger. But there’s a consolation: french …

French Fries### Video: Does being cold make you sick?

Being cold can’t give you a cold … or can it?<p>Eleanor Imster has helped write and edit EarthSky since 1995. She was an integral part of the …

### How Animals See the World - Issue 11: Light

Some animals, including your pets, may be partially colorblind, and yet certain aspects of their vision are superior to your own. Living creatures’ …

San Francisco### Fibonacci Lemonade

How would one make mathematical cuisine? Not just food that looks mathematical (like math cookies), but something that you truly have to eat and …

Lemon Juice### The Math Behind Pixar Movies

Tony DeRose is Pixar's Senior Scientist, and he uses math to make movies. In this TED-Ed talk, he explains to kids how basic math functions within …

### The Pythagorean Theorem

<b>Introduction</b><p>Have you ever pondered where mathematical equations come from or how they were derived? If the answer is yes, I want you to think if you …

Mathematics### Mathematicians solve 60-year-old problem

A team of researchers, led by Rensselaer Polytechnic Institute professor Yuri Lvov, has found an elegant explanation for the long-standing …

Mathematics### Free Games and Apps

Welcome to <b>Math Games</b>, the most trusted source for free math games and <b>skill practice</b> online. Simply select a grade, skill or game to get started in …

### Math is forever

With humor and charm, mathematician Eduardo Sáenz de Cabezón answers a question that's wracked the brains of bored students the world over: What is …

### How It Works: Death By Black Hole

A quantum quandary<p>As you fall feet first across an event horizon—the point where nothing can escape the black hole’s gravitational pull—you don’t feel anything change. But eventually, gravity is so much stronger at your feet than your head that you’re stretched apart, like Play-Doh, until you snap. …

Quantum Mechanics