Acrylic or wool for kids' sweaters - which team are you on?

I made my nephew a little hoodie when he turned two and I went with a washable acrylic-wool blend for exactly the reason you're describing. His mum once told me she does laundry for him pretty much every day, and anything that needed hand washing would have ended up shoved in a drawer forever. The blend held up surprisingly well, honestly. Three years later it still looks decent and my sister says it just goes in the machine on a normal cycle with everything else. That said, I did a cotton cardigan for a friend's baby and the difference in feel was real. Cotton is lovely and breathable for summer, but it gets heavy and stretches out once a toddler is dragging sleeves thru puddles and snack crumbs. It also takes ages to dry, which matters more than I expected.

For something a toddler lives in, I'd pick easy care every time. If you want a bit more of that nice natural fiber hand feel, a superwash wool or a wool blend labeled machine washable is the middle path. Regular wool, even soft merino, gets felted into a lump fast once it hits a hot wash or a tumble dryer, and that will happen eventually no matter how careful the parents are. A sweater in moss stitch in a washable fiber is honestly the right call. He can wear it to pieces and that's the best ending for a first wearable.

I'm in the cotton camp for little ones, honestly. I made my daughter a cotton cardigan when she was about eighteen months and the difference in how it sits on her is noticeable compared to the acrylic bits she got as gifts. The acrylic ones sort of stand away from her body and get stiff looking, while the cotton one drapes and breathes, which matters when she's running hot at the park and refusing to take her jumper off. The tradeoff is real though. Cotton grows. That cardigan got noticeably longer after a few wears and washes, and it takes ages to dry compared to acrylic. I ended up washing it and drying it flat over a towel rack every time, which her dad definitely does not do when I'm not around. My honest take is that for a first wearable, the acrylic choice was right. You learned the construction, the finishing, the seaming, all on a fibre that forgives everything. Save the fancy natural fibres for the second garment, when you know the pattern works and you can justify the cost of good yarn. One thing I'd add for anyone going cotton with toddlers: pick a machine washable cotton and check the dye takes a beating. Tomato-based stains set in cotton far worse than they do in acrylic, and that pale blue in your sweater would be my worry.

That birthday timing is so satisfying, I bet he wore it all day. I'm still working on my first blanket so a whole sweater sounds like magic to me. One thing I keep wondering about when people make kid clothes, do you make it bigger on purpose so they grow into it? My cousin's boy seems to jump two sizes every few months and it seems like anything handmade would barely get worn before it's too small.

For my niece's sweater I used a bamboo-acrylic mix and that's what sold me on blends. The bamboo gave it enough drape that the moss stitch actually showed properly instead of standing up all stiff, and it went through the wash constantly without losing shape. My sister still puts it on her for nursery runs two winters later. The other thing nobody warns you about with pure acrylic on kids' stuff is pilling where the sleeves rub against highchair trays and car seat straps. Soft yarn plus daily friction equals fuzzy elbows by month three. Anything with a bit of bamboo or cotton in it seemed to resist that way better in my experience.

Also, size up generously. She wore hers over a vest for ages so it got a whole extra season out of it.