Lesson 4

Measuring Mass

Est. Class Sessions: 3

Daily Practice and Problems

Teacher Notes
X
  1. 8 + 6 = 14                                                 14 − 8 =  6

    6 +  8 = 14                                               14 −  6 = 8
  2. 10 +  5 = 15                                              15 − 5 = 10

    15 = 10 + 5                                                 15 − 10 = 5
  3. 9 +  9 = 18                                                18 −  9 = 9
  4. Responses will vary. Possible response: It is a double. If you reverse the addends, it is still 9 + 9.

Ongoing Assessment

Use DPP item I to assess students’ abilities to determine the unknown number in an addition or subtraction sentence involving three whole numbers for the facts in Group F [E13].

I. Fact Families

  1. 8 + 6 =                                                 14 − 8 =

    6 + = 14                                               14 − = 6
  2. 10 + = 15                                              15 − 5 =

    15 = + 5                                                 − 10 = 5
  3. 9 + = 18                                                18 − = 9
  4. Why does the fact family for Question C have only two facts?