Earthworms and Yeast and Beans, Oh My!

Much of our time this week was spent doing lab work, which is fun and exciting for just about everyone!  We continued to focus on identifying and describing characteristics that differentiate living organisms from non-living things, so we got up close and personal with some earthworms  to examine how they demonstrate characteristics such as internal organization, growth, reproduction, response to environment, and adaptations within the species.  Students seemed to enjoy watching the earthworms slither around on paper plates while they (students, not worms) made observations and did some research.


We learned about the different organ systems earthworms possess, including circulatory, nervous, reproductive, digestive, and muscular.  Students researched growth, reproduction, and adaptations of earthworms and observed how earthworms responded to stimuli such as light, touch, and water drops!

Students check for earthworm responses to various stimuli, including light and touch.

Later in the week we investigated a "mystery matter" to determine if the seemingly inanimate material was actually living.  Students set up test tubes of mystery matter with different amounts of food (sugar) and warm water.  They noted the smell, turbidity, frothiness, and balloon inflation at the beginning of the investigation and again after 24 hours had passed.  Many students were able to identify the mystery matter as yeast, but it was more difficult for them to determine whether or not the yeast was living- it just looks like little pellets of sand or rock!  

Students set up test tubes with "mystery matter," sugar, and water

We noted that the smell in the test tubes was much stronger after 24 hours and the balloons had inflated.  We eventually were able to reach the conclusion that the yeast was alive- it was using the chemical reactions of its metabolism to "eat" the sugar for energy and was producing carbon dioxide gas and alcohol as waste products.  Later in the year we will talk in more detail about this process of fermentation that yeast use to produce usable energy, so it will be nice to be able to reference back to observations that students made during this investigation.

Test tubes with balloons at the beginning of the investigation

Test tubes with balloons after several hours- balloons inflated due to carbon dioxide gas produced by the yeast.

To end the post I want to quickly mention another investigation that is happening in our classroom.  I will say more in a future post, but student groups spent last week designing an experiment to investigate the effects of acid rain on the germination of bean seeds.  This week they set the experiment up on Monday and have been checking the seeds each day throughout the week.  Next week students will make final conclusions and write a lab report based on their results! 

Stay tuned for more information about how our bean seeds responded to acid!