Slider (of a plastic baggie)

Slider (of a plastic baggie)
 

This appears in a list of kindergarten supplies for the classroom:

Gallon, Quart, Sandwich and Snack size SLIDER close plastic bags

bolsas de plástico que cierran con un ________:?:

Bolsas de plástico con cierre. :)

(Although this might be different for other regions.)

A Latin American friend of mine said that when he was a child the word
corredera was used for zipper. This surprised me because I have always
thought the word for zipper was cremallera or cierre.

Thanks. I used the suggestion of someone who said: bolsas de plástico con cierre deslizante.