What happened before the lesson?

Where did the idea come from? 

• A PBS Mathline video entitled “Sand Babies” It is part of the Elementary School Math Project and can be found online. [PDF, 299KB]

What had the children learned BEFORE this lesson?
They had classified objects as heavy or light using a balancing scale.  

What did you plan to do AFTER this lesson?
Children will share their babies with their friends and write stories about how they have grown (see lesson Walking the Circle).  

What's happening during the lesson?

Objective: Children will make sand babies that match their weight and length when they were born. They will then compare their birth weight and height with their current weight and height.

Introduction:
Show children a card that contains their birth weight and length.
NOTE: Because of conditions at the time of their birth, some children did not have birth weights or lengths. In those cases, we just used the average birth weight and length for children in the United States. 

Procedure:

1. Children weigh themselves on a scale. 
2. Children add sand to a large plastic bag until the weight approximates their birth weight. 
3. Children compare their weight to their baby weight.
4. Children add a paper strip to their bag that is the measure of their birth length.
5. Children compare the paper strip to their height. 
   

What will I do after the lesson?

How did your plans change as you taught this lesson?
The process shown on the videoclip worked the best to help children make their sand babies. The conversation between the teacher and the child was critical to this lesson and the measurement terms involved both weight and length.

How would you describe the teaching that occurred using the words on the Continuum of Teaching Behaviors?   
Both teachers CO-CONSTRUCTED the sand babies so they were accurately and safely made.