Look at this number on the board: 3,650.

When you say a big number, your voice says it in parts. We call each part a chunk. Here, "three thousand" is one chunk, and "six hundred and fifty" is the next chunk.

Now say it in your head, the way you would tell someone the score at a match or the number of people at a concert.

The interactive shows each number with place-value blocks. Say each one aloud with the class and match every chunk you hear to its column. Notice what happens when a column is empty.

Now we work through this together. When I read a four-digit number aloud in words, one of you will come up and build it in the Th, H, T and U columns.

Now we work through these numbers together: 1,205 → 3,090 → 7,016 → 9,400.

What we learned today

• We say a four-digit number in chunks: thousands first, then hundreds, tens and units
• A missing chunk in the words is a warning that a column is empty and needs a zero
• We can move both ways: from digits to words, and from words back to digits

Coming up

Next, we will take these four-digit numbers apart in a different way, splitting them into thousands, hundreds, tens and units to see how one number can be written in more than one way.