Number Concepts to 100
Warm-up
Show 47 with base-ten blocks. How many tens? How many ones? What is the number? Then reverse: I say 63, you show it with blocks. What does the 6 mean? What does the 3 mean? The 6 means 60, not 6. The position changes its value.
Explore
Place value decomposition challenge: each student receives a two-digit number card and must show it three ways: base-ten blocks, place value mat (tens + ones), and a number sentence (67 = 60 + 7). Then decompose in a non-standard way: 67 = 50 + 17 = 40 + 27. Both are still 67. Why?
Consolidate
Practice
Students decompose 8 two-digit numbers into tens and ones, classify 10 numbers as even or odd, and place 5 numbers on a benchmark number line. Exit ticket: show me 73 in two different ways using tens and ones.
Exit ticket
Students decompose 8 two-digit numbers into tens and ones, classify 10 numbers as even or odd, and place 5 numbers on a benchmark number line. Exit ticket: show me 73 in two different ways using tens and ones.
In 57, the 5 is in the tens place: its value is 50 (five tens). In 75, the 5 is in the ones place: its value is 5 (five ones). Same digit, different position, completely different value. This is the essential place value insight.
Look at the ones digit: 4. Even ones digits (0,2,4,6,8) make even numbers. 84 is even. Check: 84 cubes can be paired with none left over. Or: 84 = 42 pairs of 2.