Place Value: Tens and Ones ends on comparison. Students count base-ten blocks for numbers including 24 and 37, break numbers apart in both directions (3 tens and 6 ones = 36, and 62 back into tens and ones), then write >, < or = between pairs such as 27 and 72, under a reminder that the open mouth of the symbol points to the bigger number.
1.NBT.2
“Understand that the two digits of a two-digit number represent amounts of tens and ones. Understand the following as special cases: 10 can be thought of as a bundle of ten ones - called a "ten." The numbers from 11 to 19 are composed of a ten and one, two, three, four, five, six, seven, eight, or nine ones. The numbers 10, 20, 30, 40, 50, 60, 70, 80, 90 refer to one, two, three, four, five, six, seven, eight, or nine tens (and O ones).”
Parts 1 and 2 pass numbers back and forth between block pictures, tens-and-ones language and numerals.
1.NBT.3
“Compare two two-digit numbers based on meanings of the tens and ones digits, recording the results of comparisons with the symbols >, =, and <.”
The 27 versus 72 pair in Part 3 makes the tens-first argument unavoidable: same digits, different values.
Rod-and-cube diagrams, like 2 vertical ten-rods with 4 unit cubes. Students record the tens, the ones and the total; the key runs 24, 37, 15 and on.
Both directions in one grid: 3 tens and 6 ones = ______, then 62 = ______ tens and ______ ones.
A reminder callout covers >, < and =, then large-type pairs to compare, opening on 27 ______ 72.
Sequence before the comparing lesson
Do Parts 1 and 2 the day before you teach comparison. Part 3 then lands on ground already prepared.
Ask for the sentence
When marking Part 3, have students read each answer aloud as 'is less than' or 'is greater than'. The symbols stick faster with the words attached.
27 versus 72 on the board
If you display one item, display this one. It settles the digits-are-interchangeable misconception in a single example.
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