Numbers to 120
Lessons in this chapter
About Numbers to 120
Magic with More Numbers is where place value becomes explicit. Kindergarten showed kids tens and ones; this chapter names the parts and asks them to use the names.
Count, Read and Write Numbers up to 120 and Find Before, After and Between in Numbers up to 120 extend the range past 100. The reason it is 120 and not 100 is that stopping at 100 lets kids treat it as the end of the number system, and crossing it shows the same pattern just keeps going.
Identify Place Name, Place Value and Face Value in 2 Digit Numbers makes the distinction most of later arithmetic rests on. In 47, the face value of the 4 is four, its place name is tens, and its place value is forty. Kids who have those three apart can explain why column methods work instead of just following them.
Write Two-Digit Numbers in Expanded Form and Standard Form then writes it down: 47 as 40 + 7. This is the notation that makes regrouping make sense in the next chapter, and it is the same idea that returns years later with decimals and with polynomials.
Each of the four lessons opens as a worksheet in the page. Identify Place Name, Place Value and Face Value in 2 Digit Numbers and Write Two-Digit Numbers in Expanded Form and Standard Form are the place value worksheets here, and they are the ones that make regrouping readable in the next chapter. All four are free and marked as you go.
Frequently asked questions
Four lessons. Count, Read and Write Numbers up to 120 extends the range, Find Before, After and Between in Numbers up to 120 keeps the order secure, Identify Place Name, Place Value and Face Value in 2 Digit Numbers names the parts of a two-digit number, and Write Two-Digit Numbers in Expanded Form and Standard Form writes 47 as 40 plus 7. This is Number and Operations in Base Ten (1.NBT) in the Common Core.
Because stopping at 100 makes it look like a boundary. Carrying on to 120 shows the pattern continues past it, which prevents a surprisingly common stumble at the hundreds mark.
Face value is the digit itself, so in 47 the 4 has a face value of four. Place value is what the digit is worth where it sits, so that same 4 has a place value of forty.
The name of the column the digit is in: ones, tens, hundreds. In 47, the 4 is in the tens place and the 7 is in the ones place.
Writing a number as the sum of its place values, so 47 becomes 40 + 7. It makes the structure of the number visible, which is what makes regrouping understandable later.
Because every written method depends on it. Column addition, borrowing, decimals and rounding all work because a digit's position tells you its value.