here is a website that will teach you some scales for your grade. if you are doing a grade soon and you are stuck with your scales, play the first two notes of the scale over and over again. keep doing this until you get a good rhythm. Then move on to the second and 3rd note and play that over and over.
Keep going till you get a good rhythm. Once you have done that play the 1st 2nd and 3rd note over and over. Get a good rhythm and move on two the next notes once you have done the whole scale it should be stuck in your memory. I hope this helps.
Trumpet scales are more important than you may think. if you learn all your scales you will be able to play any piece of music someone gives you.