Rename tenths as hundredths while preserving value and digit place.
The original lesson PDFs remain version 1.0.0. This supplement adds diagnostic probes, teaching responses, and question-specific rubrics. Use the supplement below for the updated guidance.
Ask for an explanation or drawing before choosing a response. A wrong answer alone does not identify its cause.
Question-by-question misconception guide and open-response criteria
Use these as follow-up prompts, then examine the learner’s model or explanation. Open responses may differ from the sample while satisfying the criteria.
c1: Write 0.3 as a fraction.
Strip model: 1 same-sized whole, each divided into 10 equal parts; 3 parts are shaded altogether.
Watch for: Confuses tenths and hundredths or drops the zero that fixes a digit’s place.
Try: Use a 100-cell square. Shade three complete columns for 0.3 and three cells for 0.03. Name these 30 hundredths and 3 hundredths before writing the decimals.
c2: Write 30/100 as a decimal.
Watch for: Confuses tenths and hundredths or drops the zero that fixes a digit’s place.
Try: Use a 100-cell square. Shade three complete columns for 0.3 and three cells for 0.03. Name these 30 hundredths and 3 hundredths before writing the decimals.
c3: Compare 0.4 and 0.40. Choose <, =, or >. The wholes are the same size.
Watch for: Thinks a final decimal zero changes value, or inserts a zero into a different place.
Try: Repartition three tenths into thirty hundredths on the same square. Write 0.3 = 0.30, then shade 0.03 separately to show why moving the 3 into the hundredths place changes its value.
c4: 7/10 = ?/100. Enter the numerator.
Watch for: Changes one part of a fraction without scaling numerator and denominator by the same factor.
Try: Shade 2/3 of a fixed strip and split each third into two equal parts. Count four shaded sixths out of six. Write ×2 on both arrows and check that the shaded endpoint did not move.
c5: Write 0.09 as a fraction.
Watch for: Confuses tenths and hundredths or drops the zero that fixes a digit’s place.
Try: Use a 100-cell square. Shade three complete columns for 0.3 and three cells for 0.03. Name these 30 hundredths and 3 hundredths before writing the decimals.
c6: Compare 0.6 and 0.60. Choose <, =, or >. The wholes are the same size.
Watch for: Thinks a final decimal zero changes value, or inserts a zero into a different place.
Try: Repartition three tenths into thirty hundredths on the same square. Write 0.3 = 0.30, then shade 0.03 separately to show why moving the 3 into the hundredths place changes its value.
c7: Calculate 3/10 + 4/100. Show a model or your reasoning.
Watch for: Combines numerator counts before making the fractional units alike.
Try: Overlay thirds and fourths on the same whole to make twelfths. Rename 1/3 as 4/12 and 1/4 as 3/12; combine seven twelfths. Ask which original amount would change if only its denominator were replaced.
c8: Write 0.25 as a fraction.
Watch for: Confuses tenths and hundredths or drops the zero that fixes a digit’s place.
Try: Use a 100-cell square. Shade three complete columns for 0.3 and three cells for 0.03. Name these 30 hundredths and 3 hundredths before writing the decimals.
s1: Write one tenth as a decimal.
Watch for: Confuses tenths and hundredths or drops the zero that fixes a digit’s place.
Try: Use a 100-cell square. Shade three complete columns for 0.3 and three cells for 0.03. Name these 30 hundredths and 3 hundredths before writing the decimals.
s2: Write two tenths as a decimal.
Watch for: Confuses tenths and hundredths or drops the zero that fixes a digit’s place.
Try: Use a 100-cell square. Shade three complete columns for 0.3 and three cells for 0.03. Name these 30 hundredths and 3 hundredths before writing the decimals.
s3: Write 0.10 as a fraction.
Watch for: Confuses tenths and hundredths or drops the zero that fixes a digit’s place.
Try: Use a 100-cell square. Shade three complete columns for 0.3 and three cells for 0.03. Name these 30 hundredths and 3 hundredths before writing the decimals.
s4: Compare 0.2 and 0.20. Choose <, =, or >. The wholes are the same size.
Watch for: Thinks a final decimal zero changes value, or inserts a zero into a different place.
Try: Repartition three tenths into thirty hundredths on the same square. Write 0.3 = 0.30, then shade 0.03 separately to show why moving the 3 into the hundredths place changes its value.
h1: Explain why 0.3 = 0.30 with repartitioning.
Watch for: Thinks a final decimal zero changes value, or inserts a zero into a different place.
Try: Repartition three tenths into thirty hundredths on the same square. Write 0.3 = 0.30, then shade 0.03 separately to show why moving the 3 into the hundredths place changes its value.
Look for in the response:
- Represent three tenths of one fixed whole.
- Split each tenth into ten hundredths to obtain thirty hundredths.
- Conclude 0.3 = 0.30 because the selected amount is unchanged.
h2: Does 0.03 equal 0.3? Use place value.
Watch for: Confuses tenths and hundredths or drops the zero that fixes a digit’s place.
Try: Use a 100-cell square. Shade three complete columns for 0.3 and three cells for 0.03. Name these 30 hundredths and 3 hundredths before writing the decimals.
Look for in the response:
- State that 0.03 and 0.3 are unequal.
- Name them as three hundredths and three tenths.
- Explain that three tenths equals thirty hundredths, ten times three hundredths.
h3: Show 0.47 as tenths plus hundredths.
Watch for: Confuses tenths and hundredths or drops the zero that fixes a digit’s place.
Try: Use a 100-cell square. Shade three complete columns for 0.3 and three cells for 0.03. Name these 30 hundredths and 3 hundredths before writing the decimals.
Look for in the response:
- Decompose 0.47 into 0.4 + 0.07.
- Name four tenths and seven hundredths using the correct places.
- Check that 40/100 + 7/100 = 47/100.
h4: Invent a pair of decimals with different written lengths and equal value.
Watch for: Thinks a final decimal zero changes value, or inserts a zero into a different place.
Try: Repartition three tenths into thirty hundredths on the same square. Write 0.3 = 0.30, then shade 0.03 separately to show why moving the 3 into the hundredths place changes its value.
Look for in the response:
- Give a pair of decimals with different numbers of written decimal places.
- Make the values equal, such as 0.5 and 0.50.
- Justify equality by renaming tenths as hundredths or appending only a final zero.
e1: Compare 0.3 and 0.30. Choose <, =, or >. The wholes are the same size.
Watch for: Thinks a final decimal zero changes value, or inserts a zero into a different place.
Try: Repartition three tenths into thirty hundredths on the same square. Write 0.3 = 0.30, then shade 0.03 separately to show why moving the 3 into the hundredths place changes its value.
e2: Why can a zero be added at the end of 0.3?
Watch for: Thinks a final decimal zero changes value, or inserts a zero into a different place.
Try: Repartition three tenths into thirty hundredths on the same square. Write 0.3 = 0.30, then shade 0.03 separately to show why moving the 3 into the hundredths place changes its value.
Look for in the response:
- Name 0.3 as three tenths and 0.30 as thirty hundredths.
- Explain the ten-hundredths-per-tenth relationship.
- State that the final zero changes the written form while preserving the amount selected.