Base Ten Models: Determine how many tens and ones are in the first number. Create the first number using 1 ten and 3 ones. Repeat the process for the second number, 1 ten and 9 ones. Identify if you have enough ones to compose a tens block. (ten ones = 1 tens block) by adding your ones together, 9 + 3 = 12 ones. Compose a ten by using 10 ones and 2 ones will be leftover. Add your tens together plus the 1 ten you composed, 10 + 10 +10
= 30. Your answer would be 3 tens and 2 ones which is 32.
Number Line: Start with your greatest number, 51. Look at how many tens are in the second number, 2 tens.
Add 2 tens to the first number which is 71, make big jumps to represent each ten you add. Then, look at how many ones are in the second number, 3 ones. Add 3 ones to 71, by making little jumps to represent each one added. The answer is 74. (You can also start with 23 or you can count by ones first).
Hundreds Chart: Start with your first number, 47. Look at how many tens are in the second number, 2 tens.
Add 2 tens to 47 by going down two rows of the hundreds chart since each row represents adding a ten, which is 67. Then, look at how many ones are in the second number, 5 ones. Add 5 ones to 67 by moving five spaces to the right since each one space equals one. The answer is 72. (You can also start adding your ones first).
Break Apart: Determine the value of the tens place in each number, 30 and 40 and then add them together which is 70. Then, look at the value of the ones place in each number 6 + 7 and add them together which is 13.
Then, add the values together which is 70 + 13, so the answer is 83.
Base Ten Models: Determine how many tens and ones are in the biggest number. Create the first number using
2 tens and 1 ones block. Look at your second number, 15. Subtract your ones in the second number from the ones in your first number. (1-5). If you have more ones in your first number you will need to decompose a ten block to make 10 ones. Add your 10 ones to the ones in your first number, 10 + 1 = 11. Then, subtract your ones from both numbers, 11 – 5 = 6. Then, subtract your tens that you did not decompose 10 - 10 = 0. Your answer would be 6 ones.
Number Line: Start with the biggest number, 72. Look at how many tens are in the second number, 2 tens.
Subtract 2 tens from 72 by making big jumps to represent each ten subtracted, which is 52. Then, look at how many ones are in the second number, 3 ones. Subtract 3 ones from 52 by making little jumps to represent each one subtracted. The answer is 49. (You can also subtract your ones first).
Hundreds Chart: Start with the biggest number, 47. Look at how many tens are in the second number, 2 tens.
Subtract 2 tens from 4 tens by going up two rows of the hundreds chart since each row represents subtracting a ten, which is 27. Then, look at how many ones are in the second number, 5 ones. Subtract 5 ones from 27 by moving five spaces to the left since each space subtracted equals one. The answer is 22. (You can also start with your ones first).
Break Apart: Determine the value of the ones place in each number, which is 2 – 3. You can’t do that so you need to decompose a ten from the tens place. 80 – 10 = 70. Then, we add the 10 ones we decomposed to the ones, 10 + 2 = 12. Then, we subtract the ones, 12 – 9 = 3. Next, we subtract the tens, 70 – 30 = 40. Lastly, add the tens and ones together, 40 + 9 = 49.
Second Grade Math, Marking Period 2, Part 1