Pounds and Ounces

10 min

Narrative

The purpose of this Warm-up is to elicit observations and questions about pounds and ounces in a familiar context, which will be useful when students reason about the relationship between the two units later in the lesson.

Launch

  • Groups of 2
  • Display the image.
  • “What do you notice? What do you wonder?”
  • 1 minute: quiet think time
Teacher Instructions
  • “Discuss your thinking with your partner.”
  • 1 minute: partner discussion
  • Share and record responses. 

Student Task

What do you notice? What do you wonder?

Picture of a recipe. List of 5 ingredients.
Picture of a recipe. List of 5 ingredients. 14 ounces of rice. 1 half pound of ground beef. 2 cans parentheses 2 pounds of kidney beans, drained and rinsed. 1 Jar parentheses 24 ounces of picante sauce. 12 ounces of shredded cheddar cheese.

Sample Response

Students may notice:

  • The list seems to be a recipe for a rice-and-beans dish.
  • The recipe shows five ingredients.
  • There are some whole numbers and some fractions.
  • The amounts are shown in different units (ounces, pounds, cans, and jars).
  • Two cans of kidney beans are 32 ounces. 

Students may wonder:

  • What dish is it? 
  • What are pounds and ounces?
  • Why are some ingredients listed in two units—cans and pounds, or jar and ounces?
     

Synthesis

  • “Can you tell which ingredient we need more of and which we need less of?” (We can tell we need more rice than cheddar cheese, or more kidney beans than beef, but it’s hard to tell which item we need in the greatest or least amount because the ingredients are not all listed in the same unit.)
  • “Which item requires the greatest amount? Which one requires the least amount?”
Standards
Building Toward
  • 4.MD.1·Know relative sizes of measurement units within one system of units including km, m, cm; kg, g; lb, oz.; l, ml; hr, min, sec. Within a single system of measurement, express measurements in a larger unit in terms of a smaller unit. Record measurement equivalents in a two column table. <em>For example, know that 1 ft is 12 times as long as 1 in. Express the length of a 4 ft snake as 48 in. Generate a conversion table for feet and inches listing the number pairs (1, 12), (2, 24), (3, 36), …</em>
  • 4.MD.2·Use the four operations to solve word problems involving distances, intervals of time, liquid volumes, masses of objects, and money, including problems involving simple fractions or decimals, and problems that require expressing measurements given in a larger unit in terms of a smaller unit. Represent measurement quantities using diagrams such as number line diagrams that feature a measurement scale.
  • 4.MD.A.1·Know relative sizes of measurement units within one system of units including km, m, cm; kg, g; lb, oz.; l, ml; hr, min, sec. Within a single system of measurement, express measurements in a larger unit in terms of a smaller unit. Record measurement equivalents in a two-column table. <span>For example, know that 1 ft is 12 times as long as 1 in. Express the length of a 4 ft snake as 48 in. Generate a conversion table for feet and inches listing the number pairs <span class="math">\((1, 12)\)</span>, <span class="math">\((2, 24)\)</span>, <span class="math">\((3, 36)\)</span>, …</span>
  • 4.MD.A.2·Use the four operations to solve word problems involving distances, intervals of time, liquid volumes, masses of objects, and money, including problems involving simple fractions or decimals, and problems that require expressing measurements given in a larger unit in terms of a smaller unit. Represent measurement quantities using diagrams such as number line diagrams that feature a measurement scale.

20 min

15 min