Bernalda 28 Novembre 2005-12-05 Classe 4^

Ins. Antonietta Lombardi – Rosa Valerio




Children of fourth class had not followed a science literacy program last year.

In the previous weeks we have discussed on properties of objects and materials.

Today I gave them some bags, backing powder, plastic glasses, a bottle of vinegar. “What can you do using all these five objects?

“We can taste them: backing powder tickles, vinegar is sour…”

“but we cannot taste all: not the bag nor the lace! So we have to think for other solutions. If you gave us the glass, this means that we can pour backing powder or vinegar in it. Better vinegar, because backing powder doesn’t make dirty. Then we have to put all these stuffs in the bag because you told we must use all five objects. The lace is to seal  the bag.”


So they started to put backing powder inside the bag, the glass with vinegar. They helped each other holding the glass to prevent its knocking over and closed tightly (“as my mom when she prepare the bags for the freezer”) their bags with the laces.


Class photo All student tightly closed their bag, before testing for an interaction

 “What’s the plate for?” they ask for. A child said that it is to prevent vinegar spilling on the desk, in the case the bag would break. They discussed on why the bag might break up asking: “can we mix the two materials inside the bag and see what’s happen? Perhaps that bag might burst and break.”

 They begun to shake the bag and soon fell into silence: everyone were observing the “white froth” producing noise, the bag that was swelling and vinegar becoming cold.

“Teacher! All it’s changed!”

“So try to understand what can be happened”, the class-teacher asked the children to tell their opinion one a time.

“backing powder and vinegar have mixed, produced froth with bubbles like Coca Cola. But air cannot come from the outside. The bag was sealed. Air cannot come in.”

“The air was the one from the bubbles that were formed!”

“Mine got more swelled because I made more froth swirling it quickly”



particolare1.jpg Backing powder interacting with vinegar in the plastic bag

“Backing and vinegar change each other, they transform themselves. Vinegar makes an action on the backing powder, makes it change” “backing also makes the vinegar change! It became darker!”

A child propose to write on the blackboard: vinegar and backing powder and all changes: froth, colour, air inside the bag.


VINEGAR          ---------------->      BACKING POWDER


                                    BACKING POWDER  --------------------------------->      VINEGAR


                                           FROTH              COLOUR               AIR


Teacher: so the vinegar acted on the backing and the bascking acted on vinegar. Can we say that they acted on each other? Vinegar and backing powder have INTERACTED. Can you tell me some examples of objects that interact one each other?

“water and sugar: we perceive it because water become sweet (evidence of interaction, note of the teacher)…

Children propose to repeat the experiment nex time, without closing the bag: air didn’t escaped from the bag, it was like a closed machinery.