Two Containers ^[solution]

The solution consists of eight steps.

Step 1. Fill up the 7L container.

Step 2. Pour all the water from the 7L container into the 11L container.

Step 3. Fill up the 7L container again.

Step 4. Pour the water from the 7L container into the 11L container till the 11L container is filled up. Three liters are left in the 7L container now.

Step 5. Empty the 11L container.

Step 6. Pour three liters of water from the 7L container into the 11L container.

Step 7. Fill up the 7L container again.

Step 8. Pour all the water from the 7L container into the 11L container adding seven liters to three liters which were already in the container. Now the 11L container contains ten liters of water.