4MA1

LO4

Breaking Apart Numbers

Formative Assessment:

- What is mental math?

Describe what it means to break apart a jigsaw puzzle.

Describe the breaking apart of an egg.

Which breaking apart makes sense in terms of a number amount, such as 10?

Instructional Strategies or Activities:

1. Divide students into groups. Each group needs snap cubes and number cards 5 – 9.

2. A student randomly draws two number cards to form a pair of addends. Students use their knowledge of order and grouping to experiment breaking apart and rearranging the addends to see which arrangements make addition easier.

3. They model the addends with snap cubes or counters, demonstrate the rearrangements they find, and then discuss which ones facilitate addition.

4. A group member records the addends, how they were broken apart and rearranged, and which kinds of rearrangements worked best.

5. Students take turns drawing addends, rearranging them, demonstrating the groupings with snap cubes or counters, and recording findings.

Summative assessment:

1. Discuss the ways you found. How many were there?

2. Have students write an explanation in their math journals about how they might break apart a group of 10 objects without changing the total.