As an Early childhood science educator who also has many years of teaching behind me (and has never used a behavior system of any kind), i have to say i am very distressed that a genuine question about how to manage kids during science activities was immediately answered with a suggestion to use a reward/punishment system for controlling children's behavior. Why do we keep using these methods when there are so many positive guidance strategies available to us that promote kids' positive self-concepts, support active collaboration rather than passive compliance, reinforce their natural desire for social acceptance, and motivate them to do and learn--many available on the NAEYC website: https://www.naeyc.org/resources/topics/guidance-and-challenging-behaviors-- these are aimed at kids from 0-8 but also applicable to older kids.
It is especially important to use positive rather than negative discipline strategies in science because our primary goal must be to maintain and nurture children's love of science, and the research is clear that many kids-- particularly Black, Latinx, and girl children--lose their motivation to do and learn science by middle-school. Black and Latinx children are-- not surprisingly--also more likely to be monitored and called out by teachers for bad behavior-- I don't believe that is a coincidence. And never ever muddle up a child's behavior with the science activity. If you punish kids by making them repeat a science lab they already did or by pulling them out of a science activity, you are actually making the science the punishment.
That being said here are a few ideas:
The most important thing you can do is make sure you are planning and introducing activities/explorations/"labs" in ways that are meaningful to kids and that engage them in investigating phenomena directly. There is nothing that begs for bad behavior more than a boring lesson. The second best thing you can do is have all the materials ready and waiting so kids are not waiting for you to prepare or get stuff together.
Think of your job as creating the structure for the activity; and within that structure embed opportunities for children to have choices.
Create a set of simple and positive rules -- along with children-- about the behaviors that will be expected of everyone. What rules do they think are most important and why? Share with them which ones are most important to you and why.
Begin the activity by drawing out their prior experience/knowledge/thinking related to the topic. What questions do they have? What are they wondering? Accept and acknowledge all their answers--this is what they are thinking and there will be misconceptions. Chart these for display and reference later....as "what we think"
Introduce the activity, being sure that it is clear to them what they are being asked to do and to record.
And yes, it is a great idea to pre-assign kids to groups intentionally based on balancing their strengths, needs, language abilities....don't use moving kids after the fact as a punishment though!
During the direct investigation, circulate among groups talking with kids about what they are doing, noticing, recording, and thinking about. If difficult behaviors arise, deal witht hese individually not publically! There is no reason ever to shame or embarrass a child in front of their peers!
After the direct investigation pull kids together for a conversation about what they did, what they observed, and what they think now. Have their ideas changed? How/how not? What interesting questions have emerged? How could they investigate more closely?
Most important of all, always communicte the assumption that kids want to and will behave well and don't mistake excitement about the investigation for negative behavior. I saw a first grader reprimanded last week (sit down now or i will clip you down on your chart!) because she was so excited when her partner's mealworm crawled off the plate that she jumped up and called out...look, they can jump!!
For many teachers, this approach involves a shift in thinking-- from a role that is about "training" kids to a role that is about facilitating children's learning (including their social-emotional learning) -- my hope is that as this approach becomes the norm in pre-service programs, it will become more typical in classrooms as well. Good luck to you Jennifer!!