I'm starting a contemporary dance class soon and my mom says I need to learn my middle (straddle) splits. Any help is appreciated!

You can research YouTube with your moms permission and guidance for videos demonstrating how to do it proper. Also what warm ups your going to need to get you into shape for many dance moves. After that its practice practice practice...

There is no "fast" way, there is just the right way, as noted, see how to do it, YouTube is great for that and then practice and practice and do it some more.

You could stretch. Like if you have a step put one legs on the step and the another on the floor.