**"Water Jars" from Coolmath.com**

Today's challenge is another one of my favorite web games. It's called "Water Jars" from www.coolmath.com. See the screenshot below.

**Grade Level:**This website is more suited to the reasoning skills of upper elementary/ middle school students.

**Objective:**Measure 6 liters of water from a 5-liter jug and a 7-liter jug

**Task:**Fill-up the jars and use them to measure 6 liters of water. The jugs can be emptied, refilled, and transferred to the other container multiple times until the goal is achieved.

For example, if you fill up the 5-liter jug and then pour it into the 7-liter jug, you can refill the 5-liter jug and pour it into the 7-liter jug leaving 3 liters in the 5-liter jug. You've just measured 3 liters.

Students will need to make moves like the one above to measure 6 liters.

Note: This is a challenging task, but it is possible. I've had students master this task in the past!

**Ways to Utilize the Activity:**This website is a great way to get your student thinking about how to solve problems such as these. Consider displaying the website to the class and review the directions. Then, as a class, discuss ways to approach the task. Ask questions such as:

- What is the task asking us to do?
- What special conditions do we need to consider?
- How can we measure different amounts, other than 5 liters or 7 liters, using these two jugs? Let's try to measure 3 liters.
- What's the purpose of being able to fill the jug and transfer it to the other jug?

This applet makes a great fast finisher activity. It can also be included on a math menu or used on a menu of problem solving station options.

**Variations:**This activity can be simulated in the classroom with actual jugs of water. Set the situation up by saying that you need to measure ____ liters of water but you only have a ____-liter jug and a ____-liter jug. Try using this model to support the students' understanding of the task before using the website for struggling students or younger students.