Welcome! Today we'll learn how to add numbers within 20 using place value blocks. Place value blocks are visual tools that help us understand numbers. Tens rods represent groups of ten, while ones cubes represent individual units. These blocks make addition easier to see and understand.
Now let's solve an addition problem: 14 plus 5. First, we represent the number 14 using place value blocks. We use one tens rod, which represents 10, and four ones cubes, each representing 1. Together, they show us that 14 equals 10 plus 4.
Next, we represent the second number, which is 5. We use 5 ones cubes to show the value 5. I'm using green cubes to make it easier to see the difference. Now we have both numbers represented with blocks: 14 shown with one tens rod and four yellow cubes, and 5 shown with five green cubes.
Now we combine all the blocks together. We have one tens rod worth 10, four yellow ones cubes worth 4, and five green ones cubes worth 5. When we count all the ones cubes together, we get 4 plus 5 equals 9 ones cubes. So our final answer is 1 ten plus 9 ones, which equals 19. Therefore, 14 plus 5 equals 19.
Sometimes we need to regroup when adding. Let's try 17 plus 8. We start with 1 ten and 7 ones for 17, then add 8 more ones. This gives us 1 ten and 15 ones total. Since we have more than 10 ones, we regroup 10 ones into 1 more ten. So 15 ones becomes 1 ten and 5 ones. Our final answer is 2 tens plus 5 ones, which equals 25. This regrouping process is essential for addition within 20.