When teaching science at the elementary level, look for curricula that provide many hands-on experiments. Students who are engaged with the material will be more motivated to learn. The curricula should also allow teachers to present the material in different ways so that all types of learners can be reached. Other skills like math and communication should be incorporated as well. The content should be organized into themes that build upon one another so that students understand the topics on a deeper level.
The backbone of any elementary science lab must be the district's approved curriculum and standards. But supplementing those can help the science lab stand out from the typical science lessons in the elementary classroom. Some curricula that provide many hands-on experiences, communication skills and different ways of presenting the material included Ethos, Foss and Insights by the Center for Science Education.
The National Science Teachers Association has a list of thousands of materials it recommends for science education. On the search page, you can choose what sort of materials you want (such as books, kits or DVDs), which grade levels (such as K-4 or K-8), and then you can type in specific words (such as "science lab" or "inquiry-based"). Junk Lab and Toy Lab, by Michael Elson Ross, are two books sure to be popular with elementary school students.
In the science lab, teachers have the opportunity to do things that might be distracting in the regular classroom. Growing an indoor garden, hatching butterflies or chicks and constructing a volcano are all science experiments that would work in the lab. PBS Kids also has a long list of easy experiments that are categorized by science subject. Kids can make soap-powered boats, door alarms and balloon cars with simple directions from this site.