Problem
"At least 2" means 2 is allowed, and "less than 4" means 4 is not allowed. So the tens digit can be 2 or 3.
A first grader can list which whole numbers sit between 2 and 4 by counting on the number line.
1.NBT.B.2Make A Systematic List"Greater than 6" means 6 is not allowed, and "at most 8" means 8 is allowed. So the ones digit can be 7 or 8.
Reading 'greater than' and 'at most' carefully tells a young learner which endpoints to keep and which to drop.
1.NBT.B.2Make A Systematic ListPairing each tens digit with each ones digit lists 27, 28, 37 and 38.
Building a two-digit number means choosing a tens digit and a ones digit, which is exactly what place value means.
1.NBT.B.2Make A Systematic ListThere are 4 numbers in the list. The pattern is that 2 tens choices each give 2 ones choices, so the total is 2 groups of 2.
Sorting the numbers into a group for tens-digit 2 and a group for tens-digit 3, each with the same size, makes the count easy to see.
K.MD.B.3Look For A PatternThe list holds 2 groups of 2, so there are 4 such numbers.
Each allowed tens digit can be joined with each allowed ones digit, and every different pairing writes a different number.
Both tens digits carry the very same 2 choices for the ones digit, so the whole list is two equal groups of two.
Find which digits are allowed in each place, then pair them up and count: 2 tens choices times 2 ones choices gives 4 numbers.