Here are three sets of relabelled blocks. Read each one aloud as a decimal:

• Set A: two rods.
• Set B: three small cubes.
• Set C: one tiniest cube.

The interactive shows four decimals made from place-value blocks, each in the units, tenths, hundredths and thousandths columns. Notice which columns are empty and how we write the zeros that hold them.

The interactive shows the blocks for ten thousandths equal to one hundredth, and ten hundredths equal to one tenth. Look at how ten of one size match the next size up, and what happens each step down.

Each step down is ten times smaller. To go from one whole all the way to one thousandth we step down three times: ten times, then ten times again, then ten times again. That is 10 × 10 × 10 = 1000, so one thousandth is a thousand times smaller than one whole.

Now we build some together. When I call a decimal, one pupil comes up and builds it on the place-value mat using the U / t / h / th columns. Everyone else watches the screen and reads the in-words readout aloud with the class before we agree it is right. We will do five or six of these, taking turns at the board.

Today we work through five decimals together: 0.008, then 0.052, 0.306, 1.009, and 2.405. Build each one on the mat and use the Check button to confirm it before we move on. The holding zeros catch people out, so we'll say each one aloud first.

What we did today

• We relabelled the base-ten blocks so the flat is 1, the rod is 0.1, the small cube is 0.01 and the smallest cube is 0.001.
• We built decimals to thousandths and matched each block to its place-value column.
• We learned to say the holding zero aloud so 0.207 is never read as 0.27.
• We saw that each step down is ten times smaller, so a thousandth is a thousand times smaller than a whole.