Zoom in. See the hundredths.

SparkClass

Compare decimals and add tenths to hundredths—one whole at a time.

CCSS 4.NF.C.5–C.7
Live Comparison
40 squares vs 38 squares
Decimal A
0.40
40/100
On A Number Line0–1
>
Decimal B
0.38
38/100
On A Number Line0–1
01

0.40 has 2 more hundredths than 0.38. Compare the value, not the number of digits.

Decimal A0.40
>
Decimal B0.38

Teacher notes: make the place value visible

Ask students to predict before they move a slider. The visual should confirm or challenge their reasoning—not replace it.

1

Compare like-sized parts

Use 0.4 vs 0.38. In the 100-square view, students can see that 0.4 is 40 hundredths. Ask why 0.38 is smaller even though it has more visible digits in the comparison.

2

Zoom without changing value

Switch between 10 strips and 100 squares. In the strip view, partial tenths remain visible, so values such as 0.38 are still represented accurately. Use 0.5 vs 0.50 to discuss equivalent names.

3

Add only after rewriting

In Add mode, connect each teal row to 10/100. The gold squares are additional hundredths. The equation deliberately keeps a denominator of 100; it never combines 10 and 100 into 110.

CCSS alignment: 4.NF.C.5 — express tenths as hundredths and add the fractions. 4.NF.C.6 — use decimal notation for tenths and hundredths. 4.NF.C.7 — compare decimals to hundredths with visual models and record >, <, or =.