Many people who send their kids to AIS live in and around "Serangoon Gardens" (bounded by Ang Mo Kio Avenue 3 in the north and Lorong Chuan/Boundary Road in the south) and "Serangoon" (bounded by Lorong Chuan/Boundary Road in the north an Braddell Road in the south). Serangoon Gardens is a "landed" housing estate meaning you have an assortment of houses (terraces, semi-detached, and freestanding/bungalow). There are few
condominiums in this suburb. Serangoon itself has a variety of
condominiums if you prefer these. The children should be able to catch bus public transport to/from school.
For transport links you have a few options. The nearest MRT stations are Serangoon (under NEX Mall) and Lorong Chuan. There is a feeder bus from Serangoon Gardens Circle (adjacent Chomp Chomp foudcourt) that connects to Serangoon MRT. Total commute time using the feeder bus and train to CBD is around 45+ minutes. There are premium buses that serve Serangoon Gardens/Lorong Chuan area (a few pick up points) before heading direct to CBD for $4 one-way. These take around 35 minutes commute time. On the other hand commute time to CBD is around 25 minutes by car/taxi during peak.
Btw, rental for houses are much cheaper now compared to 2 years ago, and in many cases you can get a much larger
property for the same rent as an apartment in the same location.