2. Week 4 Together in your groups… There are 10 kinds of people in the world. Those who understand base 2 and those who don’t. Write a sentence or two to explain why this joke is funny. Try to sneak in an explanation about place value and base 2. Children often know how to count (much higher than 10) before they learn about place value. Write a couple sentences explaining how this may help or hinder their understanding of place value.

4. Agenda Don’t forget to initial attendance sheet! Moving on to addition! Homework-online! Be sure to check course web page often (I would bookmark the 302A page, not the assignment page. I don’t want you to miss any announcements!)

5. Begin Addition Ways to represent addition: 1.Counters 2.Number Line 3.Part-Part Whole a b c 0 2 4 6 8 10

6. Vocabulary A + B = C A and B are called Addends C is called the Sum Since A + B = B + A every time, we give it a special name: commutative property. Since A + (B + C) = (A + B) + C every time, we give it a special name: associative property.

7. Addition and Place Value If we have 154 + 69

8. Mental Arithmetic 39 + 57

9. Mental Arithmetic 39 + 57 Leading digit (30 + 50) + (9 + 7) Compensation (40 - 1) + 57 Compensation (40 + 57) - 1 Break and Bridge (39 + 50) + 7 Compatible Numbers (39 + 51) + 6

10. The name of the method is not important Sit on your hands--you may not write! 68 + 74 How did you do this? How might children do this?

11. You try… Mentally: 23 + 96 Using Base 10 blocks: 89 + 323

12. Mental Arithmetic Vs. Algorithms

13. Explain the math 348 + 472 10 11 7 820 (Groups of 10) (Groups of 100)

14. Explain the math 471 + 299 10 160 600 770 How is this different from the previous problem?

15. Assignment Due Wednesday: (textbook) Read the rest of 3.1 Due Friday: Textbook: Section 3.1 p. 150-151 #5, 6, 10, 24