Is this a effective crunch/ab exercise?

Well, I've been doing these crunchs that seem like they are working or effective but I don't know for sure. Basically, you lie on the back in a sit-up position, but you hand are flat on the floor or your stomach and you lift the legs up, working your...

abs, and you lift your legs up to your chest. I've been doing these for a little bit along with pushups and situps but I want to know if these are also good.

yeah thoes are great, the work out both upper and lower abs, but focus on your lower abit more, so combination of those and sit-ups are great, also to make it more challenging try doing them with straight legs.

sweet, thanks.