Lesson 4

Unit Designs

Est. Class Sessions: 1–2

Developing the Lesson

Part 2: Skip Counting and Adding to Find Area

Students work in pairs to complete the Find Area With Square Units pages. Ask students to think of as many ways as they can to count the square units in the figures. Use Questions A–B to discuss different strategies with the class.

Ask:

X
  • What would be a good and fast way to count the square units in Question A? (Possible response: Count by twos: 2, 4, 6, 8, 10, 12, 14).
  • Can we count the square units in Question B the same way? Explain your thinking. (Possible response: No, make parts, count the big rectangle by twos: 2, 4, 6, 8, 10; then add on the two square units that stick out, 11, 12).
  • What other counting strategy can we use? (Responses will vary.)

Encourage students to first check each problem to see if it can easily be divided into smaller parts and then count the square units in the parts by skip counting.

When students finish the Find Area with Square Units pages, have each pair meet with another pair and share their counting strategies.

Ask:

X
  • What number sentence did you write for Shape F? (e.g., 8 + 3 = 11 or 4 + 4 + 3 = 11).
  • Why did you do so? What counting strategy did you use? (Possible response: I made a big rectangle with 2 rows and skip counted: 4, 8; then counted on three more: 9, 10, 11.)
  • Can you match the numbers in your sentence to the parts of the shape? (Possible responses: Yes, the big part is the 8 then the 3 more going down. Yes, the 4 + 4 is 8 for the big rectangle then 3 more.)

Use the same prompts to discuss the shapes in Questions G–H. Emphasize the importance of partitioning the shapes into easier parts to count.

Student Guide:
Student Activity Book: 213 214
Answers
X
SG_Mini
+
X
SG_Mini
+
Master: