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# Tiny Units

### Tiny Units

Cells are super small, so it's helpful to know some units that are smaller than millimetres.

A typical cell is $0.01-0.1 \space mm$ across. How many cells does that mean you can fit next to each other within a millimetre?

A) 1 cells B) 1-10 cells C) 10-100 cells

Imagine you are studying a cell that is $0.02 \space mm$ across

Those zeros and decimals could get quite confusing, so it's useful to use units that are even **smaller** than a millimetre.

Pick all the units below that you think are **smaller** than a millimetre.

You can select multiple answers

Micrometres are abbreviated $\mu m$

You can fit $1,000 \space \mu m$ inside a millimetre!

Now, imagine a cell that's $0.02 \space mm$ across. If you changed the unit to micrometres, would the number then be bigger or smaller than $0.02$?

A) Bigger B) Smaller

To convert $0.02 \space mm$ into micrometres, you need to _____________ $0.02$ by $1,000 \mu m$.

A) multiply B) divide

What is $0.02 \space mm$ in micrometres?

For every $1 \space mm$, you have $1,000 \space \mu m$

So you go from millimetres to micrometres by multiplying by $1,000 \space \mu m$ For example, $0.02 \space mm$ is the same as $20 \space \mu m$

What is the abbreviation you use for nanometres?

A) $\mu m$ B) $nm$ C) $pm$

Nanometres are even smaller than micrometres

There are $1,000,000 \space nm$ in a millimetre!

So how would you change $0.02 \space mm$ into nanometres?

A) Multiply by $1,000 \space nm$ B) Multiply by $1,000,000 \space nm$

What would $0.02 \space mm$ be in nanometres?

For every $1 \space mm$, you have $1,000,000 \space nm$

So you go from millimetres to nanometres by multiplying by $1,000,000 \space nm$ For example, $0.02 \space mm$ is the same as $20,000 \space nm$

What is the abbreviation you use for picometres?

A) $\mu m$ B) $nm$ C) $pm$

Picometres are even smaller than nanometres

There are $1,000,000,000 \space pm$ in a millimetre!

So what would $0.02 \space mm$ be in picometres?

For every $1 \space mm$, you have $1,000,000,000 \space pm$

So you go from millimetres to picometres by multiplying by $1,000,000,000 \space pm$ For example, $0.02 \space mm$ is the same as $20,000,000 \space pm$

Recap

Micrometres, nanometres and picometres are all smaller than a millimetre

**Micrometres** are abbreviated $\mu m$

**Nanometres** are abbreviated $nm$

**Picometres** are abbreviated $pm$

These are tiny tiny units!

There are $1,000 \space \mu m$ in a millimetre. There are $1,000,000 \space nm$ in a millimetre. There are $1,000,000,000 \space pm$ in a millimetre.

Now! For every $1 \space mm$, you have $1,000 \mu m$ and $1,000,000 \space nm$. How many nanometres does that mean you can fit in a micrometre?

So you can fit $1,000 \space nm$ in one micrometre. How would you change for example $25 \space \mu m$ into nanometres?

A) Multiply by $1,000 \space nm$ B) Multiply by $1,000,000 \space nm$

What would $25 \space \mu m$ be in nanometres, then?

For every $1 \mu m$, you have $1,000 \space nm$

So you go from micrometres to nanometres by multiplying by $1,000 \space nm$ For example, $25 \space \mu m$ is the same as $25,000 \space nm$

How would you convert from nanometres to picometres?

A) Multiply by $1,000 \space pm$ B) Multiply by $1,000,000 \space pm$ C) Multiply by $1,000,000,000 \space pm$

How would you convert from micrometres to picometres?

A) Multiply by $1,000 \space pm$ B) Multiply by $1,000,000 \space pm$ C) Multiply by $1,000,000,000 \space pm$

Now! How would you convert from nanometres to millimetres?

A) Multiply by $1,000,000 \space nm$ B) Divide by $1,000,000 \space mm$

Make sure you know if you are going to a smaller unit or to a bigger one!

If you go from bigger to smaller, you should **multiply** (for example from millimetres to micrometres).

If you go from smaller to bigger, you should **divid****e** (for example from picometres to nanometres).

What would $0.035 \space mm$ be in **micrometres**?

What would $75 \space \mu m$ be in **picometres**?

What would $47 \space pm$ be in **nanometres**?

Summary! Cells are only about $0.01-0.1 \space mm$ across

So it's useful to have smaller units so you don't have to deal with all those zeros and decimals.

Micrometres, nanometres and picometres

There are $1,000 \space \mu m$ in a millimetre. There are $1,000,000 \space nm$ in a millimetre. There are $1,000,000,000 \space pm$ in a millimetre.

Be careful when you convert from one unit to another!

If you go from a bigger unit to a smaller unit, you should **multiply**.
If you go from a smaller unit to a bigger unit, you should **divide**.