Does Heat Affect Kids’ Learning? What I’ve Noticed As A Classroom Teacher
Last Thursday, I stood at the front of my 4th grade classroom, wiping sweat off the back of my neck and waiting for kids to finish their weekly multiplication quiz. The building is from 1952, and we don’t have AC, just three clunky box fans that push around warm, dusty air. My little desk thermometer read 83 degrees, and half the kids had their hoodies tied around their waists, their t-shirts sticking to their shoulders. Liam, who usually finishes his quiz in 8 minutes flat and gets every question right, was still staring at the first page, his pencil hovering an inch above the paper. I walked over, knelt down beside his desk, and asked if he was stuck. He blinked at me like he’d forgotten what I was asking, then said, “My brain just feels fuzzy. I know 8 times 7 is… 56? Wait no, 48? I can’t remember.”
I’ve been teaching here for 7 years, and this pattern isn’t new. I keep a little note in my lesson plan book next to the date every time we have a stretch of hot days, and I’ve compared quiz scores over time. On days when the classroom is over 80 degrees, the average score is 10 to 18 points lower than on 70 degree days, even when we’re quizzing on the exact same material the kids practiced the week before. I noticed it at home too, with my own 12 year old son. Two weekends ago, our AC went out right before he had to memorize state capitals for a test. He kept repeating “The capital of Oregon is… Salem? No, wait… Portland?” Twenty four hours later, when the AC was fixed, he rattled off all 50 without stumbling.
I used to think it was just distraction—kids were uncomfortable, so they weren’t trying. But a couple of years ago, I looked up what actual research says about heat and learning, and it turns out it’s not about effort. Heat raises the core temperature of your body even just a little bit, and that makes it harder for the part of your brain that handles working memory to do its job. The knowledge is still there, stored away. But the heat makes it way harder to pull that knowledge out when you need it, or to add new information to what you already know. So to answer the question I’ve seen parents asking online: yes, heat absolutely affects how we can use and access the knowledge we’ve worked to build.
After Liam had that fuzzy brain moment last week, I didn’t make him sit there and struggle. I pulled one of the frozen water bottles I keep in a cheap cooler by the door and handed it to him, told him to go stand by the open door in the shade for three minutes, hold it against the back of his neck. When he came back, he wrote down 56 for 8 times 7 and finished the rest of the quiz in 10 minutes.
The frozen water bottle trick is one of the first small changes I made, and it’s totally low effort. You just fill clean bottles up the night before, throw them in the freezer. I tell all my parents to do this for big test days: send a frozen bottle instead of just cold tap water, and tuck a small damp washcloth in a zip top bag. Kids can wipe their face or neck if they get overheated, and it doesn’t disrupt the whole class. It makes a noticeable difference for most kids, and it costs almost nothing.
Other small adjustments I’ve settled into over the years work just as well. I never schedule big tests for afternoons on hot days. I swap them to first thing in the morning, when the classroom hasn’t had time to heat up from three hours of sun pouring through the south-facing windows. If we have to do new work after lunch, I break it into 15 minute chunks, with 5 minutes of slow walking outside in the shade between chunks. You don’t need to do a whole recess to reset, just get kids out of the hot room for a minute to lower their core temperature a little.
For parents doing homework at home, the same logic applies. If it’s a 90 degree night, don’t insist your kid sit at the neat desk you set up in the sunlit front room. Let them do work on the cooler tile floor of the hallway, or on the couch right by the fan, or even in the car with the AC running if that’s the only cool spot you have. If your kid says they can’t think straight, don’t automatically write it off as an excuse to skip work. That’s the biggest shift I’ve made, both as a teacher and a mom. It’s not laziness, it’s a physical effect on their brain.
This week, we had three straight 86 degree days, and even with all the little tricks, we still had a lot of fuzzy brains. I pushed the upcoming science test to next week, and most of the parents I talked to were glad, not upset. The district finally approved funding for new AC for all the older buildings, but it won’t be installed until the 2026 school year. Until then, we just keep adjusting. Some days it works really well, and kids can still show what they know. Some days, we just do read alouds in the shade and catch up when the air cools down. I used to feel guilty for changing plans, like I was falling behind on curriculum. Now I know it’s just meeting kids where they are. The knowledge is still there, it just needs a little cool air to come out.
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