It all comes down to their age and skill level. Kids of different ages might still be within the same swim level, in which case they could both take the swim lesson together. Keep in mind, little swimmers tire out faster than their older siblings, so pairing children of similar age is the best option. Ultimately, speaking to your swim instructor will give you the best options that you have in order to provide your children with the most effective lesson. One swim instructor can teach up to 3 students per half an hour, or 6 students per hour overall. For more advice on swim lesson grouping and swim levels, contact our head office at 1-888-950-7946, or info@aquamobileswim.com. All of our customer service reps are also certified instructors who can help answer any swim-related questions, in addition to helping book you and your family.