When her son was the only one in his class not invited to another child's birthday party, a Canadian mother decided to use it as a "teachable moment" about Down syndrome.

Jennifer Kiss-Engele posted an open letter to the other parent Thursday on Facebook. In the message, she pointed out that her son, Sawyer, was the only child out of two dozen kids in the class who was excluded. Kiss-Engele wrote that her son didn't expect to be invited to every party, pointing out that only a few friends were asked to celebrate Sawyer's last birthday.

"I know it's not because he's mean, you couldn't meet a happier child," she wrote. "I know it's not because he's not fun, he has a great sense of humour and an infectious laugh. I know it's not because your child and him don't get along, he's brought up your child's name on several occasions. The only reason why you decided it was OK to not invite my son to your child's birthday party is because he has Down Syndrome."

Kiss-Engele went on to write, "I am sorry that you are not informed, maybe scared, or uncertain about what it means to have Down Syndrome. I know if you knew more about Down Syndrome you wouldn't have made this decision. I am not mad at you. Rather, I think this is an opportunity for you to get to know my son better."

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"People with Down Syndrome want the same things that you and I want," she wrote. "They want to have close relationships, they want to feel love, they want to contribute, they want to have meaningful lives, and they want to go to birthday parties. It may be more difficult at times to understand my child. But the laughter and love that you share doesn't need interpretation."

Kiss-Engele admitted that she felt "scared, uncertain and misinformed about Down Syndrome" before her son was born, and worried that Sawyer and his siblings would have trouble relating to each other. But she said having a brother with special needs has made her other children "compassionate individuals who know that just because you may be a little different that others, that it's OK."

She encouraged the other parent to talk with their child.

"They will remember the time that their parent said to them, it's not OK to leave someone out because of their disability, race, or gender," Kiss-Engele wrote.

As of Friday night, Kiss-Engele's post had been shared more than 1,600 times and received hundreds of comments, overwhelmingly supportive.

"Amazingly worded," one person commented. "I too have a son with special needs and it is so sad how people leave them out of things. I know that many times it is because they think they may not be able to participate, but it sure would be nice if they asked anyway. They may be surprised at what a children with special needs are capable of."

Another woman said even though she didn't know Sawyer or his mom, they would be welcome at her son's birthday party this fall.