The teacher was "the opposite of calm" as she tried to tell the toddler to get out of bed and go to the mat, the colleague said.
The girl, who was lying on her stomach on a small bed a short distance off the floor, was simply not responding to the teacher's commands.
It was then that the teacher picked the girl up by the back of her sweatshirt, lifted her off the bed, and dumped her on to the floor, the colleague said.
"It was enough for me to walk briskly over. I mean, I was really shocked . . . it was a decent drop."
It's estimated the girl was dropped on to her front from a height between 60cm and a metre.
"It wasn't a hard force but it was aggressive . . . it was done like she was dropping a sack of spuds.
"She was on her front and I remember there was a pause before she got upset because I think she was stunned about what happened. I remember saying to [the teacher] 'what are you doing? You don't treat children like that.' And [she] apologised to her."
The colleague said if she had walked in to see her own child being treated that way, "Hell would have broken loose".
She picked up the child and cuddled her as the girl cried.
The colleague said the teacher had a tendency to get "very heated" when children were not complying with her wishes.
"Spilling of water or something, it didn't need to be much.
"Don't get me wrong she has some beautiful, quality, lovely teaching moments, but when she lost her temper she really lost it," she said.
"I know that [she] was unwell and we all had great empathy for her."
The teaching team were often on edge, while the children were "startled and nervous" because of it, she said.
The teacher's lawyer, Ben Paradza, pointed to a statement the colleague signed, which said the teacher picked up the child and moved her across to the floor. He said whether the colleague saw the child "moved to the floor" rather than dropped on the floor might raise questions of credibility.
But it was then pointed out that the following line in the statement included a clarification that the girl was not on the floor when the teacher let go of her.
He also challenged the colleague's belief the handling of the child was "rough", particularly if she was using both hands to grab the child's clothing.
"She wants to ensure that she has got full control full grip of that child in moving it across. Don't you agree?"
The colleague said picking any child up by their clothing was inappopriate and threatening.
Giving evidence herself, the teacher said she knelt by the bed and picked the girl up by one hand and put her down on a thick, shaggy mat.
"Everything's just been blown out of proportion. I never placed her down like a sack of spuds," she said.
The child was a "rough and ready tomboy" who she "loved to pieces" and had cared for as a baby.
The teacher said she was frustrated having to work with her colleague, who she said did not pull her weight.
The teacher's case is being heard by the tribunal throughout today.
