For the 'Different House Pics' activity, children are asked to look at the pairs of house pictures and describe/list similarities and differences between houses in the past and houses today. This can be done orally or in written form. As your P3 will soon realise, most 'differences' are because of advances in technology.
The 'Houses in the Past' task is a lovely way for your P3 to get involved with an older family member/grandparent/family friend. I usually set this as a project homework which takes up to a week and is presented to the class as a talking and listening exercise.