Down to thousandths

• CCSS-M · 5.NBT.A.3
  Read, write, and compare decimals to thousandths.

5.NBT.A.3 asks children to read, write and compare decimals to thousandths. Placing 0.125 and 0.375 next to hundredths cards forces the comparison across place values, which is the comparison the standard names.

Some children will know 0.125 as one eighth. Encourage that link; it makes the placement a halving problem rather than a guess, which matters when only 0 is showing at first.

1. Start: 0 at 8.3%
2. Drop 1: 1 at 91.7%
3. Drop 2: 0.5 at 50.0%
4. Drop 3: 0.25 at 29.2%

When to dropAfter two cards, drop 1 to fix the whole, then 0.5 to halve the line, then 0.25. The quarter marks make 0.125 an obvious halving once they are down.

Drop unlocks after 2 cards placed.

• 0.125

  at 18.7%
  One eighth as a decimal. Halfway between 0 and 0.25.
• 0.375

  at 39.6%
  Three eighths. Between 0.25 and 0.5.
• 0.7

  at 66.7%
  Seven tenths, in the upper half.
• 0.05

  at 12.5%
  Five hundredths, close to 0. Contrasts with the thousandths cards.
• 0.875

  at 81.2%
  Seven eighths. Between 0.75 and 1, near the end.

• 0.125 is one eighth. Where does one eighth go?
• Is 0.05 bigger or smaller than 0.125? By how much, roughly?
• 0.375 and 0.7. Which is nearer to a half?

• Looks like
  0.125 placed larger than 0.375 or 0.7.
  Means
  Reading the longer decimal 0.125 as the larger number.
  Respond with
  Ask how many thousandths are in each, or link 0.125 to one eighth and 0.375 to three eighths.

Ask which cards are also eighths, and write 0.125, 0.375 and 0.875 as eighths to close the loop.

Thousandths sit between the hundredths, and a decimal like 0.125 has an exact place you can find by halving.