Measuring Objects Using Metric Units Unit of Study 8 : Measuring Length and Perimeter Global Concept Guide: 2 of 3

Content Development  Approximately 4 days should be spent on generating estimations and measuring using metric units: centimeter, millimeter, decimeter and meter.  Allow students to measure real objects rather than just pictures on paper.  Use rulers with the zero mark a short distance from the edge. This tool will force students to think about both endpoints when measuring and to focus on units when they measure.

Day 1  The focus of Day 1 is to make a connection to prior learning in 2 nd grade and to compare metric units to customary units.  Use Connect to Science on p.480 to help compare units.  To assess students prior knowledge of appropriate units of measure, see Unlock the Problem on p. 477.

Day 2  The focus of Day 2 is choosing the correct unit of measurement.  The students should be focusing on choosing the most efficient unit.  Misconception Alert: Students may choose a metric unit that is too small to measure efficiently. Suggest that the student describe the process that he or she would use to measure the classroom, including the number of times they would use the small unit. Then ask them how many times they would use a larger unit.

Day 3 and Day 4  The focus of Day 3 and Day 4 is representing the length of a unit in metric units. The students should be using a standard ruler.  While the students are measuring, they should be comparing and discussing the relationships between the different metric units.  Activity 2 on p. 482 should help with the discussions.  Give students opportunities to use “broken” rulers.

Day 3 and Day 4  By the end of Day 4, Students Should be Able To  Generate appropriate estimates  Measure using the most efficient unit of metric measurement  Measure with a “broken” ruler

Enrich/Reteach/Intervention  Reteach: Allow students to continue to use standard rulers to measure small sets of real world objects. You can also utilize R98 & R99.  Enrich:  E99 – Gives students practice estimating and measuring using metric units.  Enrich Activity TE 481B – Students work with objects greater than a meter long and use their prior knowledge to estimate the distance in decimeters and centimeters.