Should I tell them why??

Today was not the best day, emotionally meanly. I was faced with lots of questions coming from kids, about the age of my special needs daughter, about her skills, and her physical abilities... 

I had to say an answer, but what to say?? should I tell them why? or should I lie to just continue without explaining anything?

We had a field trip today, and some of the kids started to ask me why Ashley has an stroller? I explain something simple for them to understand, I said that she needs the stroller because she has a problem with her legs and her heart, and if she gets really tired she can get really sick. That was the end of that question but opened the door for many more.

Then I was asked if she knew who much is 4x1... I said no! 

After a few minutes the boy asked me how old was Ashley, and I said 8 years old, for what he replayed... she cant be 8 years old, and if she was she should be in 3rd grade not second... and she should know how much is 4x1.... 

My heart stopped!!! all the other kids looked at me waiting for an answer, and I just looked at them without knowing what to say, I said well, she is 8 years old, and she is not in 3rd grade because she is in your class... I had to ignore the other question... I don't want them to threat her different, but at the same time I don't want them to think that been different its wrong.

This reminded me of a conversation I had with the bis principal  a day before, she wanted me to not take the stroller because of the "looks" she said that Ashley wanted to look more like her peers and not different, but this is not about looks, this is about health, I would give anything for my daughter to be healthy and not need that stroller, I don't love the idea of having my 8 year old on a special needs stroller, I do notice all the people looking at us everywhere we go and she is in it. I hate the way they look at her and then look at me, as if she was a weird object. 

I am not ashamed and I will never be ashamed of my kids, but why are others so easy in judging? why our schools are not teaching this kids that been different its normal? why ? why the parents not talking to their kids about people with different needs and ways of life? its our job as parents to teach them equality, and its also the schools job to implement it. 

how can they expect no bullying in their school grounds if they don't want them to see "different"?  

At the end of the day, after all the kids walk for hours many told me that Ashley was so lucky because she was in her stroller and they were tired of walking. I couldn't help to think that they are the real lucky ones, because they don't need and stroller!!!