You don& want to miss out on these high quality materials that will interest your children and freshen up your classroom materials! Thank you for your interest in my Montessori Life Sciences Pack! There are 14 sets of materials (over 75 pages!
Help kids see how plant grow! (Or if you're short on kids just do it for yourself - it's pretty cool!) :: Science for Kids: Observing Plant Growth with Bulbs (with a FREE printable observation sheet!) from Buggy and Buddy
Might be easier to beef some of these up for kindergarten then try to make other activities appropriate. STEM for Preschoolers 10 Science Technology Engineering Math Ideas for 3 to 4 Year Olds Left Brain Craft Brain Pin
DIY Light Table for Preschool. there's a link at the end for a more sophisticated one. i ended up just using what i had: christmas lights, black construction paper & tape for the sides, and waxed paper & tape under the lid. did the trick for me:)
DIY Portable LEGO Kit with Free Printable Activity Cards. I like this for school, older kids can have activity cards to create planets/atoms/molecules/fractions, younger ones can practice fine motor skills.