Stomach Digestion in a Bag

Good morning scientists! Does your little one wonder what happens to their food once they swallow it?

MaterialsStomach Digestion in a Bag (3)

Ziploc Sandwich Bag

Crackers (Any Kind)

2 Lemons, Knife, Cutting Board, & Juicer OR Lemon Juice


  1. Squeeze your lemons and pour the juice into a sandwich bag. You want enough juice to fill the bag up about a third of the way OR 2 Lemon’s Worth.

2. Break a cracker up into smaller pieces to simulate chewing with your teeth. Place the cracker pieces into your bag. Seal tightly and gently mix/move around.

3. Try using your lemon juice to break down other foods.

Talking Points

Your stomach is filled with an acid. Lemon juice is also an acid. Our stomach is filled with an acid called gastric acid. Acids have a pH of less then 7 or neutral. The acid in the stomach has a pH of 1.2 to 3.5. Lemon Juice has a pH of around 2.0 making it a good substitute for the stomach acid.

Our stomach acid breaks down food and is added by the movement of the muscles in the stomach. The muscles move around to mix up the foods so that the stomach acid can further break down the foods that we have chewed up. We can hear our stomach grumble when we start getting ready to eat and as a signal that we need/want to eat this rumble sound is the sound of the stomach muscles moving around.

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