We all know that Santa has a team of reindeer to pull his sleigh around the globe on Christmas Eve delivering presents. But are reindeer really the best animals for the job? In this Nature Classroom post, we do the maths together to work out what is needed from these magical animals, and compare it with some of the wonders of nature. Why not combine some of the features of the creatures to design your own animal to pull Santa’s sleigh? We would love to see what you come up with, so please do submit it to our community gallery. For inspiration, here are some created by members of our Young Zoologists Club:

*These activities support learning in the following areas: *

- Identify how animals and plants are adapted to suit their environment in different ways and that adaptation may lead to evolution
- Read, write and compare numbers up to 10,000,000
- Solve problems involving addition, subtraction, multiplication and division
- Convert between different units of metric measure e.g. kilmoetre and metre; centimetre and metre; gram and kilogram

### How big is Santa’s Sleigh?

Santa has a lot of presents to deliver on Christmas Eve, but just how big does his sleigh have to be to carry them all? Here we do some calculations to work out how big and heavy Santa’s sleigh would be when fully loaded so we can see which animals have the strength to pull it. Let’s start with the presents themselves.

**Task: **Calculate the weight of presents carried on Santa’s sleigh and how big the sleigh would need to be to carry them.

We need some information to work this out. We have made some assumptions for our calculations. Why not try the maths yourself with some different estimates for the size and weight of the presents?

*How many presents? *

*How many presents?*

There are around 2.2 billion (2,200,000,000) children in the world. If each has one present from Santa, that’s: **2.2 billion presents.**

*How much do the presents on Santa’s sleigh weigh?*

*How much do the presents on Santa’s sleigh weigh?*

We’ll assume each present weighs 500g. There are 1000g in 1 kg. That means that 500g = ½ kg**2.2 billion presents x ½ kg = 2.2 billion ÷ 2 = 1.1 billion kg (1,100,000,000kg)**

*How big does the sleigh need to be to carry these presents? *

*How big does the sleigh need to be to carry these presents?*

We’ll assume each present is a cube 20cm x 20cm x 20cm in size and the sleigh is 20m wide with presents stacked to a height of 10m. How long does the sleigh need to be?

First we need to work out how many presents high and how many presents across this would make.

There are 100cm in 1m. 100 ÷ 20 = 5 presents to a metre.

So if we stack up the presents, and there are 5 presents to a metre, we multiply the height of the stack (10m) by 5 to find out how many presents fit into that height: **10m x 5 presents per metre = 50 presents high. **

This means that we have 50 layers of presents on our sleigh. Next we need to work out how much space each layer will take up. How many presents are there in each layer? To find this out, we just divide our total number of presents by the number of layers:**2,200,000,000 presents ÷ 50 layers = 44,000,000 presents per layer**

If our sleigh is 20m wide, we do a similar piece of maths to find out how many rows of presents there will be on the sleigh: **20m row width x 5 presents per metre = 100 presents in each row**

Now we divide the total number of presents in a layer by the number of presents in a row to work out how many rows of presents we need on the sleigh: **44,000,000 presents in a layer** **÷ 100 presents in a row = 440,000 rows of presents**

How long does the sleigh need to be to fit this many rows of presents on it? Remember there are 5 presents to a metre, so we divide the number of rows by 5 to find out how many metres long the sleigh needs to be: **440,000 rows ÷ 5 presents per metre = 88,000m **

There are 1000m to 1km, so we can convert the length of our sleigh to kilometres by dividing it by 1000. **88,000 ÷ 1000 = 88km. That is a long sleigh! **

To give you an idea of how long it is, if the front of the sleigh was at the Museum in Cambridge, the back end would be a few kilometres past the Natural History Museum in London.

Progress so far: Santa’s sleigh measures 20m x 88,000m and carries 1.1 billion kg of presents.

But that’s not the end of the story. Surely a sleigh that size must weigh quite a bit in itself? Let’s work it out.

#### How much does the sleigh itself weigh?

Let’s say Santa’s sleigh is made of pine. A large pine tree can measure 50m tall and weigh 4,000kg. But how many pine trees will we need? First let’s see what the length of the sleigh is in pine trees: **Sleigh length of 88,000m ÷ tree length of 50m = 1,760 trees to make up the length of the sleigh**

If we assume one pine tree will provide enough wood to support 2m of the width of the sleigh, and the sleigh is 20m wide: **20m sleigh width ÷ 2m width of sleigh supported by a pine tree = sleigh is 10 trees wide**

So to find out how many trees we need, we’ll multiply the number of trees long the sleigh is (1,760) by the number of trees wide (10): **1,760 trees long x 10 trees wide = 17,600 trees in total**

To work out how much they will weigh, we multiply together the number of trees with the weight of each tree: **17,600 trees x 4000kg per tree = 70,400,000 kg**

#### How much does Santa’s sleigh weigh in total?

**Weight of Presents + Weight of** **Sleigh = 1,100,000,000kg + 70,400,000kg = 1,170,400,000kg**

Let’s add to this one more weight – the weight of Santa himself. This is likely to change throughout the night, depending on how many mince pies he’s eaten, but we’ll make him quite big and jolly, weighing in at 150kg. **This makes the total weight of Santa’s sleigh: **

1,170,400,150kg

or in words:

one billion, one hundred and seventy million, four hundred thousand, one hundred and fifty kilograms** **

That’s a lot of weight for nine reindeer to pull! (130,044,461kg each to be precise).

### Who’s Strong Enough to pull Santa’s Sleigh?

Before we see if there are any animals better suited to pulling Santa’s sleigh than reindeer, let’s work out how many reindeer it would take. For the following we have looked up the data we can find on the internet – unfortunately there are not many animals that have had their strength recorded, so a lot of these data are estimates, and we have rounded it up in places to make the calculations a little simpler.

A reindeer can pull roughly its own weight behind it. That means to pull Santa’s sleigh that weighs 1,170,400,150kg will take 1,170,400,150kg of reindeer. To work out how many reindeer that is, we need to divide this weight by the weight or a reindeer. A large reindeer can weigh 150kg. So: **1,170,400,150kg ÷ 150kg = 7,802,667 ⅔ reindeer **(but as we can’t have ⅔ of a reindeer, we’ll round up to 7,802,6687 reindeer).

That’s a lot of reindeer. More than are estimated to be alive on Earth! (the IUCN Red List has an estimate of 2,890,400 mature individuals alive today).

**Task: **Which is the animals below do you think is the strongest?

Which of these animals do you think is the strongest? How many do you think would be needed to pull Santa’s sleigh? Have a guess, then see how close you are with the slideshow below.

### Who’s fast enough to pull Santa’s sleigh?

Santa has a lot of presents to deliver, so his sleigh is going to weigh a lot. But that’s not the only magical power involved. He also has a long way to travel in a short period of time. Estimates have been made that Santa has to travel 510,000,000km in the space of 32 hours. That’s a speed of 15,937,500km per hr or 4,427km per second. No animal can run, fly or swim that fast, but there are plenty of animals that can travel faster than reindeer.

**Task: **Put these animals in order of speed. Which can travel the fastest?

Cheetah ©Leszek Leszczynski CC BY 2.0 Sailfish Ostrich © Alex Derr CC BY NC SA 2.0 Pronghorns ©Mark Dyer CC BY NC SA 2.0 Peregrine Falcon © Hari K Pantibanda CC BY NC 2.0 Brown Hare © Wimog CC BY NC SA 2.0

### Who can light the way for Santa’s sleigh?

So you have an animal with extreme strength to pull Santa’s sleigh, and speed to make it around the globe delivering presents on Christmas Eve. But there is something missing – what could possibly stand in for Rudolph’s red nose, acting like a headlamp lighting the way in the dark? Bioluminescence! This is the production of light by a living organism. You may have heard of fireflies or glow worms. These insects are able to glow creating a pretty light show. But the ability to produce light is much more common in sea creatures. Find out more from this fascinating TED Talk:

### There was Dasher and Dancer and Prancer and Vixen…

Traditionally, Santa’s Sleigh is pulled by a team of reindeer: Dasher, Dancer, Prancer, Vixen, Comet, Cupid, Donner, Blitzen and, of course, Rudolph. Can you think of any other animals that suit these names and might work in place of reindeer? Here are some of the ideas of the Museum of Zoology team.