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Follow Anoushka Takla's fourth graders as they seek to answer the question: "What happens to our trash over time?"

Overview of Compost Unit

Anoushka spent two months with her fourth grade students exploring the question, How do different objects change over time? Her class placed several objects – an apple, a bagel, a leaf, a paper plate, a plastic spoon, and a piece of tin foil – in clear plastic containers of soil. They made predictions about how each object would change, and then carefully observed the objects over the course of seven weeks.

Read on to see how several notebook strategies worked together to help students build their science ideas about decomposition. To view examples of student work and to download the complete lesson plan, click the links below.

1. Weekly Observations - Investigation

Once a week, Anoushka set aside an hour and a half for observing and sketching the objects. Students kept one notebook page for each object, and used sketches and labels to communicate how each object changed or stayed the same from week to week.

Before launching the investigation, Anoushka introduced her students to scientific sketching, so they knew how to make their entries accurate, detailed, and explained.

During the observation time, the objects remained on their designated tables, and students moved around the room, progressing from object to object at their own pace. To accommodate her class of 32 students, Anoushka had two sets of each object.

2. Vocabulary Building - Notes

Anoushka circulated during the weekly observations, encouraging students to add more labels and explanations to their sketches. As they searched for words to describe what they noticed, she offered useful descriptive vocabulary. She added each word to an anchor chart she created, titled “Words to Describe Objects.” Over the course of seven weeks, the list grew.

3. Compare and Contrast - Reflection

Every two weeks, Anoushka gave students a chance to take stock of how the items were changing. Each student focused on just one item. She gave them two minutes to silently review their sketches, and to think about how that item had changed or stayed the same.

Then, she instructed them to turn and talk with a partner, using the sentence frames provided, such as “After two weeks in the soil, I notice that…”

Finally, Anoushka let them expand their thinking in the notebooks, sometimes using a T-chart, and other times writing in paragraph form.

Anoushka knew she’d need to share some science content with her students, in order for them to understand what was happening in this experiment. She wanted them to conduct the investigation first, and then offer the content just-in-time – at the moment when students had built enough context and curiosity that they really needed to know more.

So, she waited until Week 6 to introduce a text from her science textbook. After reading, students took notes in their notebooks, recording what they understood about the concepts of microorganisms and decomposition.

5. Making Sense - Reflection

After 7 weeks of observations, Anoushka had students return to their original hypotheses and use evidence from their notebooks to explain why each prediction had proven correct or incorrect.

To drive home the meaning of the investigation, she asked students to respond in their notebooks to this prompt: “Using what you’ve learned about microorganisms and waste, what are the benefits of composting?”

Anoushka finished the unit by collecting a class list of lingering questions, asking: “What are you still wondering?”

Anoushka Takla teaches fourth grade at M.H. Tobias Elementary School in Daly City, CA. She is an alumna of the California Academy of Sciences' Teacher Institute on Science and Sustainability. She loves facilitating this compost investigation because it gives students "a real-life experience that shows them that what they do, even as children, has an impact on our environment."