Illuminations: Exploration of a Balance

Exploration of a Balance

Keeping in Balance

In this lesson for grades 1‑2, students balance pairs of like and unlike objects by changing distance from the fulcrum. Students use a crayon (as the fulcrum) and a ruler to represent the balance.

Learning Objectives
 
Students will:
  • balance pairs of like and unlike objects by changing distance from fulcrum
  • record observations about the positions of the objects on the balance
  • identify patterns in their work

Materials
 
Keeping In Balance Activity Sheet
One ruler and crayon for each group
Two similar and one dissimilar paper clips for each group

Instructional Plan

To begin the lesson, activate students' prior knowledge about balances. Ask students to identify examples and uses of balances. Students may reply with any of the following:

  • scale balances
  • playground equipment
  • and so on...

 

Distribute the Keeping In Balance activity sheet to each student.

Keeping in Balance Activity Sheet Keeping in Balance Activity Sheet

Give each group of pupils a ruler, a large crayon, two similar paper clips, and one dissimilar paper clip.

Guide pupils to balance the ruler on the crayon so that the ruler is parallel to the desk. The crayon may be taped to the desk if needed. If students are familiar with the term fulcrum, ask them what represents the fulcrum in this makeshift balance. [The crayon]

 

 

Guide the pupils as they explore the movement of the ruler when a single paper clip is place at one end of the ruler. Pupils observe and describe the movement.

Guide the pupils to find the proper position for the other paper clip to rebalance the ruler.

Allow enough time for the pupils to observe the movement at various positions and to record, on the Keeping In Balance activity sheet, those positions at which the pair of clips is balanced.

Repeat the procedure for a pair of unlike paper clips. Once again, students should record their observations and findings on the Keeping In Balance activity sheet.

 

Ask students how they determined the positions of the two dissimilar paper clips. Lead a class discussion in which students share their responses.

Questions for Students
 

When the two paper clips were the same size and weight, what did you notice about their position when they balanced?

[They were the same distance from the crayon (the fulcrum).]

How did you determine the positions of the two unlike paperclips so they would balance?

[Student responses may vary, but students may suggest that they positioned one of the paperclips, and then moved the other paperclip (or both paperclips) until they balanced.]

Assessment Options
 
  1. Have students test pairs of various objects to determine which items in a pair are equal in mass, which are heavier, and which are lighter.
  2. Students may observe the positions at which the objects that are equal in mass balance.
  3. Students may observe the positions at which objects that appear to be different in mass balance.

NCTM Standards and Expectations
 
Measurement Pre-K-2
  1. Compare and order objects according to these attributes.
  2. Recognize the attributes of length, volume, weight, area, and time.
  
1 period   

NCTM Resources

Learning and Teaching Measurement (2003 Yearbook)

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