The first time I attempted to make strawberry jam, it ended up more like strawberry sauce. This is because strawberries have very little pectin, which is needed to make jam set. My mum then went on to recall a time when she was making strawberry jam, and ended up standing over the stove into the wee hours of the night, waiting for it to set.
Then, the other week when I was in the supermarket, I saw jam sugar for sale. Jam sugar has extra pectin added in, so I bought it to make jam. Following this success, strawberry jam was once again on the cards. It turned out beautifully, and there were no midnight cooking sessions. I now consider Jam sugar a must for making jams.