When they (walked/ were walking) home, they found a wallet with a huge amount of money in it!
were walking
When I was at primary school, I (was doing/ used to do) about one hour's homework a day.
used to do
As soon as Mandy (was getting/ got) Simon's text, she (was jumping/ jumped) on her bike and (was riding/ rode) round to his house to speak to him.
got - jumped - rode