How can I tell they are learning?

My second day of prac went well. So far over 2 days I've taught:

• 2 x 30 minute lessons on SOSE (see Lesson Plans)
• Literacy groups x 40 minutes
  
• Maths (small groups) - measurements/perimeters 3 x 40 minutes each
  
• Story time (whole class floor time after lunch)

It's been very interesting so far. My mentor is very supportive and is encouraging me to do lots of teaching (another lesson planned for the morning).

My question is - how do I know they are learning? I'm struggling with this the most. Sometimes I think I can tell.. other times I'm not 100% sure. We also have several special needs students and it seems almost impossible to tell (out of a group of 30) who is and who isn't learning.