As Jellyfish mentioned, you and your children will learn alot while traveling. Everyday is a day of learning when traveling, meals, petrol, accommodation costs, shopping etc.
When we went overseas the main thing the girls had to do was keep a diary. This was something they did at the end of the day and you will be amazed how much they take in. It takes a while to get into the groove but once they did they love it.
Also, talk to their school. Ask what they will need to know by the time you come back.
If you have internet you can keep in touch with the school while away