Here are our base-ten blocks again, but today the labels change. In 4th class the big cube meant one thousand and the flat meant one hundred. Today the big cube means one whole. So the flat is now one tenth (0.1) and the rod is one hundredth (0.01). Look at the smallest block, the little cube. What do you THINK it is worth now?

0.003

Watch as we build this number with the relabelled blocks. The big cube is now one whole, so the small cube is one thousandth. Three of the small cubes sit in the thousandths column. What is the same and what is different about how we used these blocks last year?

0.034

Now look at the hundredths and thousandths columns together. We read this as three hundredths and four thousandths. Which is worth more, one hundredth or one thousandth?

0.207

This time there are two tenths and seven thousandths, but nothing at all in the hundredths column. What is holding that empty column open?

1.045

Here is a whole big cube as well, plus four hundredths and five thousandths. Read each column aloud, then write it the ordinary way — that is just how we usually write the number, like 0.207.

Now we build decimals together on the place-value mat, with the columns Units, tenths, hundredths and thousandths. One pupil builds at the board while everyone else reads each column aloud — the empty columns catch people out, so we say each one. We will build these together: 0.006, 0.05, 0.408, then 1.207.

Now we work through building these decimals together: 0.008, then 0.052, then 0.306, then 1.009. Each one steps up a little, and the zeros are the part to watch. Before each build, the whole class answers one quick question: which column is empty? Then a pupil builds it and we check.