20 Month Old Throwing Tantrums

When a child is tired or over-tired, they tantrum. They do not have the advanced communication nor emotional ability... to be articulate yet. They don't even have, fully developed emotions yet, much less the understanding of the abstractness of it nor do they even know the 'words' for their feelings...much less the ability to tell you. Hence they tantrum.

I learned, that for my kids, I did not go out and do errands with them, when it was nap time. Nor when they were tired or hungry. Bad timing. Kids when tired or hungry, have, nil... patience and they get over-stimulated easily. That means, they will melt-down, easily.
When tired, and in a store or running errands, it causes over-stimulation.

Kids also, tantrum/cry... in order to SHUT-OUT... stimulation. To stop it. That is the only way they know how to communicate that. It is a coping thing.

When my kids are tired, they can't even eat... even if they are hungry.
So I always had dinner, earlier for them. Because once they were tired... they could not eat and/or would be very fussy, at dinner time.

Kids also need.... to be verbally cued... to be told what is coming up. To be given a head's up. They need to be, "transitioned" to things. Not abruptly.... having activity changed or stopped suddenly. They need to, transition.

Always also, let a child know what is coming up and what is going to happen. So they can get used to it. ie: "In half hour, after eating, we will run errands. You will sit in the cart... then we come home and nap."

Even if they 'understand'..... it does not mean they can do it. At these ages.... a child cannot necessarily do, everything that is in their heads. At these ages... there is no coordinated ability, per what is in their head's and what they can actually do.
ie: if you show and explain to a 2 year old, how to ride a 2-wheel bike. They may understand. BUT that does not mean they can do it. Because, their motor-skills and coordination... or muscle movements, are not there yet. Not like a 7 year old, in comparison.

Keep expectations, age appropriate.

At this age, they don't even have, fully developed impulse-control yet, either. And they are reactors. They don't even have cause & effect, down pat yet... nor do they even have fully developed attention spans, either. Nor do they have understanding of socialization or social skills.

Get the book 'What To Expect The Toddler Years."

I would suggest taking items with you to distract her.... small snacks (cheerios, things like that), a special small toy only for shopping trips...

Stick to your guns about staying in the cart.... when I worked in a large retail store, there were so many kids that got lost... terrifying to a parent! Also, set the standard now about her staying seated in the cart.... again, I've seen children fall.

Try to do your shopping when she is well-rested... a tired baby will be more likely to be cranky. Not always easy, I do understand!

S.H. gave a very good description of why kids tantrum and how to prevent them.

For me, the least embarrassing way to handle a trantrum in public is to leave. Pick her up, push the cart to the side and walk out of the store. You may be able to sit quietly in the car and have her regain composure so that you can go back in but mostly likely not. She may just need for you to pay attention only to her for 10 minutes or so.

As others have said, shop when she's rested and not hungry. Talk with her ahead of time about what will happen and what you expect. Coach her thru out the trip. Talk to her about what you're doing. When she's wanting a balloon, quickly get out of site of the balloon and distract her with a toy from your bag or by pointing out something you're buying and have her help you put it in the cart.

With my grandkids I found that putting a thick folded up blanket inside the cart and sitting them down with a couple of toys sometimes worked better than sitting them in the seat. They could play with the toys and handle some of the groceries. I would talk with them as I shopped. Being inside the cart cut out some of the visual stimulation.

When mine were very young I would bring them a snack or something, but never give into a tantrum. If she pitches a fit either ignore it or leave.

Avoid going out around nap time and make them help you while at the store. Either have them help push the cart, go get X or Y of the shelf. Or what my son mostly does is sit in the seat, I hand him the item (if it's not breakable) then he throws it in the cart. He LOVES doing that. He will also hold my list (I make him one since he often times will rip it or crumple it) and just chat away as if he's reading it off to me. lol