You do not need a certificate to teach your children English or foreign languages. If your family is bilingual, you will practice easily.
Asking your kids to sit down and listen to your teaching activities may cause them to get bored. You will never achieve your goal of teaching a foreign language. You may be able to make your children sit down and listen to you at one or two meetings. Yet, your children will have thousands of reasons not to study anymore.
I tried to teach my kids in simple ways without burdening them. Here are the tricks.
Can you count how many words and expressions that your children will master in a year. If there are 48 weeks in a year, your children will master 240 words and 96 expressions. You should not sit for hours like in a classical classroom when teaching English or foreign languages. What you need to do is stick to your weekly goals or objectives. Do you want to try those tricks at home? I hope the tricks will work. On the other hand, you can modify the tricks to fit your children's habits and characteristics so that your kids will not get bored.