Look at this picture
When I tell my toddler put the straw into the milk box, she often push it completely into the box. And as a result, the straw got lost inside the box.
What should we express in this situation?
Please push the straw halfway into the box! (but sometimes we need to go two-third of the straw not just halfway of the straw in order to reach the milk).
Please do not push the straw into the box completely!