Immediate Gratification Jam

This is from the book 'Joie de Vivre' by Robert Arbor.

If you like jam, try making little batches of your own. This jam will keep for a week or so in the fridge, so you don't need to use airtight jars etc...
The ratio is 1 pint fruit to 1 cup sugar.

2 pints small fruit, such as strawberries, blueberries or raspberries
2 cups sugar

If the strawberries are large, cut them into 4 wedges. The blueberries and raspberries don't need to be cut.
Toss fruit in sugar until coated, and then place fruit in a saucepan. Add enough water to come halfway up the fruit. Do not cover.
Bring to the boil, then immediately lower heat to a simmer. Stir occasionally. When the fruit has melted into liquid, check for sweetness and add more sugar if needed. When the extra sugar has melted into the fruit mixture, your jam is ready to use. It will be quite runny, but will thicken up in the fridge. Store in fridge, and use with a week.