We have been doing lots of different scientific garden investigations as part of our garden unit.

Today is all about observing weeds growing in our planter boxes.



This is a fun hands on opportunity to teach several plant science concepts.



We pulled two types of weeds from the planter boxes.   We saved some for a science experiment, a clump of grass and a broad leaf weed, I assumed was a young dandelion, but I did not check to make sure.  I do wish I had set out a book with pictures for the children to identify this weed.  But I forgot. 

We set these weeds out on a table outside for further investigating after our weeding project was through.  If you would like to read about our weeding project, read the article posted here.

We discussed how grass in a yard is not considered a weed.  But grass in our garden is a weed.  A weed is a plant we don't want to grow in our garden.  It competes with our other plants for nutrients, water, space, and sunshine.  So we remove weeds from the garden.

We soaked the smaller broad leaf weed in a glass of water.



Then laid the plant on a paper plate to dry a little in the sun.



Once some of the water dried from the root, we could see there was one long thick central root, with lots of small hairlike roots coming from it. 

This root system was very different from the roots on the clump of grass. 



Next we put the clump of grass into a bowl.  We tried to shake off as much dirt from the roots as possible.



But the dirt still clung inside the root tangle.  The roots provided a net for the dirt, and it was very hard to pull any more out.



Next, we rinsed the roots in water to remove the rest of the dirt.



This revealed a whole bunch of roots we could not see before.



After rinsing the dirt off, we took a closer look at the roots.  They were like thick hair.  Soon the children realized there was more than one grass plant in this clump.  The oldest took his tools and carefully began to separate each system of roots and plants.



He separated out 11 different grass plants with their own set of roots.  Each root system was made up of lots of long, thin roots that joined at the base of the plant, but were totally separate from each other.



He also cut a stem of grass open to see what was inside.  He described what he found inside as a thick juice, and the stem was kind of like a hollow straw. 

We talked about how this juice was from water and minerals in the soil, taken up by the roots, then moves up through the stem to feed the plant.  Kind of how people drink through a straw to drink up a milk shake.  The plant is using the stem to drink up nutrition (minerals) and water.



This was a great garden investigation today.

The children learned a great deal about what weeds are, what roots look like, and their function.  They were able pull the weeds from the soil with the whole plant in tact.  Then they were able to compare the root systems from two different plants.  Finally they observed the evidence of liquid inside the plant that showed them that the roots draw in water and nutrients from the soil for the plant to live.


How do you teach your kids about weeds, plants, and roots?  Leave us a comment.  Thanks.


This post will be linked up with
The Garden Challenge
No Time For Flash  Cards
Science Sunday