Once you can play the scale in this manner at a reasonably quick tempo without losing the rhythm, try memorizing the rhythm on one note first, and then improvising with it. Play any notes from the scale in any order you like, but be sure to keep the rhythm exactly the same every bar.
Don’t worry if your melodies don’t sound great at first, as your ear and your musical knowledge develops, improvising will become easier and easier. The following example demonstrates four bars of an improvised melody using this set rhythm.
The next step is to move the quarter note to the second beat and play eighth notes in the rest of the bar. Once again, memorize the rhythm and then improvise with it. Then repeat the process with the quarter note on the third beat of the bar, and then again on the fourth beat of the bar. The following example shows each of these rhythms as shown on one note, along with the rhythm from the previous example.