# Elevators and Number Sense

Number sense should develop early, and what simpler way to do it then to start with elevators?

Elevator, Vicenza, Italy

Why elevators you ask? Well, I just returned from 2 weeks in Italy. Partly for work: training elementary math teachers in Vicenza, Italy on College & Career Ready Standards for UT Dana Center International Fellows and Department of Defense Education Activities; and partly for leisure: touring Venice, Cinque Terre, Florence, Tuscany and Rome with my husband, sister, and brother-in-law. The first thing I noticed was the elevators have negative numbers to indicate those floors below ground zero (i.e. what we usually call floor 1 or Lobby in the U.S.)   It’s not the first time I’ve noticed this – in England, in Paris, in Germany – all these other countries indicate on their elevators the ground floor to be 0, the floors above ground 0 are 1, 2, 3…. and the floors below ground zero are -1, -2, -3….

This way of numbering elevators makes sense. Much more sense than Floor 1, or Lobby and then Basement, Basement2 (or LL1, LL2) – which is our typical way of indicating the ground floor (1) and the floors below ground level (Basements/Lower Levels). If you were a young child living in these countries and taking the lifts (or elevators), you are regularly exposed to integer numbers – with a contextual connection that the ground floor of a building is ground 0, and the floors below the ground are negative numbers, and the floors above the ground are positive numbers. It may not even be explicitly explained to young children, though they would be using the terms ‘negative 1’ or ‘negative 2’ to go down below the ground floor. They will have this repeated exposure so when they are ‘officially’ taught about negative numbers in school, they have an immediate connection to prior knowledge about the numbers in an lift/elevator and can make a real-world connection. Negative numbers won’t be new or hard to understand because it’s just the numbers in the elevator. Or – the numbers of the temperature, because let’s not forget, these countries also use the Celsius temperature scale, where freezing is 0, and anything above 0 degrees is above freezing and getting warmer (positive) and anything below 0 degrees is getting colder (negative). The further from 0 in either direction, the warmer or colder you are – again, real-world connection and a contextual understanding of integers.

Number sense. Number lines. Integers. Real-world connections. Just from elevators and temperature scales.

This repeated exposure, informal as it may be, is developing an intuitive understanding of numbers and their real-world meaning. And when students are then exposed to number lines and positive and negative numbers more formally, in a school setting, they already get what that means because it is familiar to them. They can apply what they already know to ‘mathematics’. The formalization makes sense, and connections make sense, and understanding is that much deeper.  This is different in the U.S., where students often struggle with the idea of ‘negative’ numbers and number lines and the distance from zero because we are teaching them something new.  We don’t have a real-world exposure to negative numbers because we use LL or B1 to represent lower than 0, our ground floor is never called 0, it’s 1 or Lobby or G (ground). Our temperature doesn’t have 0 as the freezing mark – it has 32 degrees Farenheit. Think how much easier it would be to connect negative numbers (those numbers smaller than zero) to negative floors or negative temperatures. Freezing makes sense at 0. Negative temperatures are colder than freezing. Positive temperatures are warmer than freezing. 32 degrees – not quite the same one-to-one connection to a number line, is it?

Anyway – my point is that something as simple as changing the numbers on an elevator to integer representations would go a long way in helping young children develop number sense early on so that by the time they get to school, they already have a natural understanding of positive and negative numbers. Early on they would be exposed to the idea of 0 being the ground level, positive numbers mean higher floors or farther away from ground zero, and negative numbers mean lower floors, below the ground, and the further you go below ground, the more negative you get, the farther away from zero you are. Number lines would then be ‘recognizable’ because there’s a contextual connection. (If we could change our temperature scale to Celsius that would be great too, though that one is a lot harder to do).

Relabel elevator buttons to reflect numbers on a number line – a simple change that could go a long way in developing informal number sense in children.

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# The Last Five Minutes of Class

You teachers out there know that those last five minutes of class – when students are ‘packing up’ even if you are not quite finished with the class activities, or, you’ve finished and they are suppose to be working on their assignments or reviewing – are often  a ‘wasted’ five minutes. In my many years at schools, I saw teachers use that time in various ways – but more often than not, it was simply time to get ready to leave, basically chat time and get your stuff together and wait time. Not productive learning time at all.

It’s easy enough to make these moments into fun, engaging, mathematics problem-solving that students, believe it or not, actually come to enjoy and request. I use to have a few different things that I would pull out – focusing on either logical thinking or number-sense or puzzles. Here are just a couple of things:

1. I had the 24-game – several different versions.  I(If you have never played this or seen this, you should explore it). So, in those last 5 minutes, I would pull out a card, write the 4 numbers on the board and students would try to reach the target of 24. As an example: 2, 3, 4, 4 and you can add, subtract, multiply or divide using each number one time, to make 24. I often had candy for anyone who could come up with a strategy.
2. If you don’t have actual cards, you can create your own version of ‘reach the target’.  So, pick 4 random numbers using a calculator, and give students a target number to try to reach (so 24). Or, choose 2, 3, or 4 random numbers with a calculator (or have students give you numbers) and ask students to use all the operations and come up with the smallest outcome and/or the largest outcome.  This is a lot of fun – you get some interesting problems and students have to explain their answers and defend their solutions.
3. Give the students a logic puzzle.  I actually purchased several logic books, and so would read one out to the students or draw/show the picture on the screen and they could work in pairs/small groups to try to come up with a solution. Great critical thinking and collaboration going on here – and if we couldn’t get the solution before the bell rang, we would take it up the next day with most of them working on it overnight. Here are some good resources for logic puzzles:
4. Read a story.  Yep. Even with my high school students, I would read stories.  Math related of course. You would be amazed at how they actually enjoyed listening, and of course, once the ‘story’ was finished (which might take a couple days depending on our actual time at the end of each class) we’d discuss the ‘math’. Some of my favorite books:

Students loved the challenge of these last 5 minutes (sometimes it would be more). It was a very competitive yet non-threatening time where they could test their math skills or thinking skills, work together, and have fun with numbers and logic. That time was no longer wasted – it became a time students actually looked forward to and often requested.

As you are nearing the winter break, there is probably a bit more time to spare or a bit more time needed to keep students attention.  Use that time in an engaging way that allows for some critical thinking, collaboration and a game-like atmosphere that challenges students and keeps those last five minutes productive.