Obtain the phone numbers of the parents in your child's class. Ask if your child's school has a directory in which student names are listed with contact information. If such a directory exists, you will not have to worry about getting permission to publish personal numbers publicly and can proceed to Step 4.
Create a contact request form. Include fields for home and mobile numbers, as well as the full names of both parents. Make it clear that the information is to be published on a phone tree and will be distributed to the class. Put an opt-out option on the form for parents who do not want to participate.
Ask the teacher to distribute the contact request form to the class and collect it the following day. Even if the teacher has the students' phone numbers, this step is necessary because through the contact form, you are gaining permission to use the phone numbers in a public manner.
Compile the phone numbers you have obtained into a master list. Determine who is likely to be the most reliable and easy to contact, and put those parents at the top of the list.
Divide your list into three to five columns. Put one reliable, easy to reach parent at the top of each column. Ask the parents at the top of the columns to call the 5 to 9 parents below them on the phone tree in the event that every parent in the class needs to be contacted.
Put your name and phone numbers at the top of the tree, as you will be responsible for calling the 3 to 5 parents heading the columns.
Select a bright color of cardstock, and print out enough phone trees to give everyone in the class one. If you are able to reduce it to a strip that can be folded into a booklet the size of a credit card, people are more likely to have it with them when needed.