Horses and Cows

Number Sense
Primary Mathematical Content
Understand and use properties and symbolic representations of real
What does the student need to be able to do?
Write the information as a system of equations and solve.
Secondary Mathematical Content
Use estimation and logic to find the solution. Use a high and low
estimate to see how the two variables relate.
How are you going to make these connections?
Students can either derive the solution algebraically or estimate
different possibilities to solve the problem.
Primary Mathematical Process Skill
Problem solving using Algebra.
What does the student need to be able to do?
Set up the problem, solve the system of equations, and interpret the
results. Students can also estimate possible values and interpret the
Assessment Question or Activity
I have 4 horses and 2 cows that are worth $6400. If I can sell one horse
and one cow for $1800, how much dies a cow cost? How much is a horse
worth? Relate this to the paint problem.
Steps: The students can:
1. Set up the information as a system of two equations: 4h + 2c = $6400
1h + 1c = $1800, and solve by
elimination or substitution.
2. Solve the situation by estimating high and low values for the data,
then using logic to
narrow the error of estimation.
Instructional Strategies
Algebra, logic, models.
Outline of Problem or Questions
I ordered 26 gallons of some special paint, then forgot how much of each
color I bought. If my 26 gallons contained both green and red paint, and
I bought 7 more gallons of green paint than red paint. How much of each
color did I buy?