how to explain combinations on a 3rd grade level

Question

Class of 22 students votes on their favorite pet.  The bird gets 3 times more votes than the snak and the bird gets 2 times more votes than the hamster.  How many votes does each pet get?

Answer 1

Third-graders do algebra using the guess and check method in conjunction with a table to track their guesses.

 

Columns in the table are labelled "Hamster," "Snake," "Bird," and "Total."

 

Squeeze in notes as necessary for the relationship between the bird's votes and those of the snake and hamster.

 

Since the bird's votes must be divisible by both 3 and 2, the bird's votes are multiples of 6.

 

Start the table by giving the bird 6 votes, the hamster 3 and the snake 2.

 

Add together 6, 3 and 2 and put it in the "Total" column.  If it does not equal 22, give the bird another 6 votes and start a second line where the bird has 12 votes.  Calculate the votes for the snake and the hamster and total all 3 in the "Total" column.  Continue until the "Total" column has 22.