I am a huge fan of cross-curricular activities because they really help drive home some topics, and they help students understand that the real world isn't as compartmentalized as school may make it seem. Science can sometimes be difficult to work into a cross-curricular framework, but this body mapping project brings art and anatomy lessons together in one fun activity.
Elementary school teachers basically need to be a jack-of-all-trades when it comes to subject matter. The National Science Teachers Association provides some guidelines for quality science education on this page (and if you explore the rest of the site). Of particular interest here is one of the sections toward the end about the importance of talking about concepts during hands-on activities since kids (and teachers) can get wrapped up in the activity and lose the focus of what's being taught.
I'm always stumped when trying to work physical education into a cross-curricular activity. This is a helpful lesson plan that explores the basics of the various body systems and what physical activities can help keep these various systems healthy.
Learning about the people behind the science can help bring abstract concepts into better focus. It's especially fun when students see women and people of color doing important work. This printable handout of a list of 18 science pioneers and brief descriptions of their contributions to science will not only inspire students, but will help tie your science lessons into social studies as well.
Kids are full of questions, and when it comes to science sometimes nice, clear illustrations work best to answer them. TED-Ed is a great resource for quick, engaging videos that help to explain complex processes or ideas. This one explains the biological processes behind healing wounds in the skin.
I have to admit that I can get a little carried away with science experiments because of just how cool some of it can be. Unfortunately, that can lead to huge messes or just overly complicated piles of stuff in the classroom. The simplicity of this experiment that illustrates the body's pulse is what was most appealing, not to mention it's cheap to execute. Also, I highly recommend a marshmallow and toothpick version because you get to eat the marshmallows afterward. Easy clean up—in my mouth!
Internal organs are pretty gross, but we'd be lost (and dead!) without them. This quirky website lets students click through internal organs and skeletal structures to find quick descriptions and connections to the other parts in the relative system.
Kids are always down for activities that use balloons, and really I am too. This is a neat experiment using balloons and cardboard tubes to illustrate how the muscles attach and manipulate the human skeleton. Did I mention I also like things that use recyclable materials that parents can help me gather? Yeah, I like that too.