Determining Relative Size: Measure Up!
At the end of this lesson, students will be able to measure objects using another object and compare the results.
Introduction (5 minutes)
- Call students together. Ask them to think about times in life when people need to know what size something is. If students are having trouble coming up with answers, suggest times when they have seen adults cooking or shopping for clothing. Ask them why they think this is important to know.
- Next, ask students how people measure these objects. Students may suggest answers like measuring cups or using a ruler.
- Ask students about times when it is very important to know the exact amount of something and times when a general idea is good enough.
- Tell students that there are formal units of measurement and show them a ruler as an example. Every time someone measures something in inches, it should always be exactly the same length.
- Ask students to look at their feet. Because students’ feet are each slightly different sizes, if everyone in the class measured something with their feet, the results would not be exactly the same. However, if the same person measured the item numerous times, the measurement should be the same.
- Tell students it is possible to compare items as long as the unit of measurement is consistent. If they use the same hand, foot, pencil, etc. to measure two objects, they can determine which one is bigger or smaller.
Explicit Instruction/Teacher Modeling (5 minutes)
- Have students brainstorm a list of things they could measure in the classroom. Leave this list posted on the board.
- As a class, choose two of the items to measure.
- Choose a unit of measurement. Examples: a piece of chalk, a marker, a pencil.
- Have a student volunteer measure the first item. Demonstrate to students how to record the item and its size on a piece of paper.
- Have another volunteer measure the second item. Demonstrate again to students how to record the item and its size on a piece of paper.
- Finally, have students write the sentence [one object] is bigger than [the other object]. on their paper.
- Show them how they can use the measurements they just found to determine how to fill in the blanks.
Guided Practice/Interactive Modeling (5 minutes)
- Divide students into small groups. Hand each group a piece of paper and a pen or pencil. Instruct students to decide as a group on two items to measure and compare.
- Then, instruct the groups to choose a unit of measurement and measure the objects. They should record the results the same way the class just did on their piece of paper.
- After the groups have measured their objects, instruct them to write which object is bigger on their paper. * During this process, any adults should be circulating, assisting, and correcting any misconceptions.
- Finally, hand each student, or pair of students, a piece of paper and instructions to compare 5 more sets of items. Ask if they have any questions.
Independent Working Time (10 minutes)
- While students are working, adults should be circulating, answering questions, and providing assistance. To avoid chaos, establishing boundaries for finding objects to compare and measure is important. If allowing students outside of the classroom, make sure that rules and acceptable items to compare and measure are clearly defined.
- Enrichment: For students looking for a greater challenge, encourage estimating before taking a measurement. Encourage students to challenge themselves to become more and more accurate in their estimates.
- Support: For students who need a little extra assistance, making this activity more structured can provide additional support. For example, setting up specific stations or naming specific items to be measured can simplify the activity. Working in partners can also be effective to scaffold this activity.
Assessment (10 minutes)
- Student involvement and engagement with the activity can be used to informally measure student growth.
- Student accuracy in measuring and comparing the length of specific items can be used to more formally assess whether or not the learning objectives have been met.
- For homework, students can also be assigned to measure things at home with their foot or other small object and compare the sizes.
Review and Closing (5 minutes)
- Call students together.
- Have each student share an item they decided to measure with and two things they compared.
- Point out how some students could get different results in the number of objects long something was, because the objects were different sizes. However, using the exact same object to measure multiple items, they can compare the size of items.