This is a new show that is coming to PBSKids. The show doesn't actually start airing until September, but PBS posted the first episode, "Ms. Mole's Glasses / Elinor Stops the Squish," freely for viewing on their video app and also on YouTube.
https://www.youtube.com/watch?v=UdMbG9MSR9EMaterial is at approximately 15:00 - Ms. Mole is erasing something on the chalkboard and the chalk dust causes her to sneeze.