Why we need negative numbers- which is the world's tallest mountain?

It's important that children be given as many opportunities as possible to see the relevance of why they are learning something in maths.

To help us deepen our understandings of how we use positive / negative numbers in real life situations, a student suggested we could look at the height of mountains and find the difference between those and the depths of oceans.

It's a great idea.

A student had remarked how Mt. Everest is the tallest mountain.

Another remarked that they thought it wasn't. It was a mountain in Hawaii.

So we used this to try to resolve mathematically.

On the data screen we found the following facts:

  -  Mt. Everest's  elevation =  8 848 metres
  
  - Mauna Kea's elevation =  4 285 metres

   -Mauna Kea's height from sea level to ocean floor is approx 6 000 metres.


Partners drew diagrams to work out what to do with those facts.

It was interesting to discover students who thought islands floated on the ocean rather than stemming and rising from the ocean floor. 

After some time, partners buddied up with others and shared their ideas.

Eventually, as a whole class we came to the conclusion that Mauna Kea is the tallest mountain in the world and Mt. Everest is the highest.

It was a great way for us to discover why we need negative numbers and made possible because of a student wondering - the foundation of great inquiry-based learning!