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New Jersey Center for Teaching and Learning Progressive Mathematics Initiative.
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New Jersey Center for Teaching and Learning Progressive Mathematics Initiative This material is made freely available at www.njctl.org and is intended for the non-commercial use of students and teachers. These materials may not be used for any commercial purpose without the written permission of the owners. NJCTL maintains its website for the convenience of teachers who wish to make their work available to other teachers, participate in a virtual professional learning community, and/or provide access to course materials to parents, students and others. Click to go to website: www.njctl.org
2nd Grade Facts 2012-07-12 www.njctl.org
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Table of Contents Facts Click on a topic to go to that section. Addition Facts Doubles Facts Making Tens Doubles plus 1 Adding 3 Numbers Doubles minus 1 Subtraction Facts Number Stories Adding & Subtracting zeros Recall from Memory Fact Families
AdditionFacts Click to return to table of contents
Jason had 5 pieces of candy. Jeremy had 3 pieces of candy. How many pieces of candy did they have all together? Draw a picture to help you count everything together. 1 2 8 5 3 4 7 6 + 5 + 3 = 8
+ If 5 + 3 = 8? Does 3 + 5 = 8? +
You can turn addition facts around and the answer will still be the same. 3 + 5 = 8 5 + 3 = 8 Turn-around facts
What is the turn around fact for 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 = + = +
What is the turn around fact for 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 + = = +
Addition problems can be written two ways. 5 + 3 8 or 5 + 3 = 8
Strategies for adding: 4 + 2 = Use a number line +1 +2 10 8 9 -10 -9 -8 -7 -6 -5 -4 -3 -1 0 1 2 3 4 5 6 7 -2
Use a number grid +1 +2 4 + 2 =
+ Use your fingers
Put the bigger number in your head and count up 4 + 2 = 4 5, 6
If the problem shows a small number first, reverse it and start with the bigger number in your head to make it easier to add. 2 + 5 = turn it around to make it 5 + 2 = 5 6, 7
Susan had 6 pieces of candy. Her sister gave her 3 more. How many pieces of candy does she have now? Use the candy to make a picture. + =
1 3 + 2 = 5? A Yes B No
2 7 + 2 = 8? A Yes B No
3 Which is the correct answer? 4 3 + 6 A 7 B 8 C
4 Which is the correct answer? 5 + 1 = 5 A 6 B 7 C
2 + 6 = 5
4 5 6 +
3 3 7 +
9 + 1 = 8
Addition Strategies Adding past 10
There are 6 bees on one flower and 8 bees on another. How many bees are there all together?
Addition strategy 1 Use a number grid - start with the bigger number and count up the smaller number.
Addition strategy 2 Put the bigger number in your head and count up the smaller number.
Number Model 6 + 8 = 14 When you add two numbers together the answer is called the sum.
Seven ants were walking in a line. Four more ants joined them. How many ants are in line now? What strategy will you use? Number model: = +
Anna had six red balloons and five blue balloons. How many balloons did she have all together? What strategy will you use? Number model: = +
Justin had 8 toy cars. He got 3 more for his birthday. How many does he have now? What strategy will you use? Number model: + =
9 What is 9 + 2? 10 A 11 B C 12
10 What is 5 8 + 13 A 14 B C 15
9 4 11 +
7 + 3 = 12
13 8 + 6 =
14 7 8 +
15 15 is the sum of which number model? 9 + 5 A 7 + 9 B C 9 + 6
16 12 is the sum of which number model? 7 + 5 A 5 + 6 B 8 + 3 C
Making Tens Click to return to table of contents