Designing Mixtures
Physical Science
Grades 2-3 | 20 sessions
Students learn about mixtures, dissolving, and the properties of substances. They also learn to consider what they already know about a topic, to use text features as they read, and to write scientific procedures. They learn and use scientific vocabulary, such as ingredient, soluble, evidence, and compare.
Approach
Do it:
Students engage in hands-on activities, such as tasting and describing the properties of various beverages. Students also design and test mixtures to act as glues.
Talk it:
Students are provided with many opportunities for small group discussions to help them make sense of science ideas. For example, students discuss their observations and predictions as they test glue mixtures.
Read it:
Students read five science books, including Handbook of Interesting Ingredients, a reference book that guides their investigations. Students use comprehension strategies such as accessing and applying prior knowledge, and learn how to navigate informational text.
Write it:
Students write procedures, including a procedure for making a glue that is both strong and sticky. Throughout the unit, students write to record observations and reflect on their learning.
Learning Goals
| Science | Literacy |
|---|---|
Science Knowledge
Science Inquiry
Nature and Practices of Science
|
Reading
Writing
Listening/Speaking
|
Science Content
The Designing Mixtures unit introduces students to important physical science concepts, including properties of substances, mixtures, and dissolving. Students also learn about the design process- an important aspect of science and technology.
Properties of substances: Students investigate properties of substances using their senses. Properties that students investigate include stickiness, solubility, color, odor, and texture. Students learn that scientists identify and sort substances based on their properties, and that different substances are useful in different ways, depending upon their properties.
Mixtures: A mixture is any combination of two or more substances mixed together. Students learn that the properties of a mixture depend on the properties of the substances in the mixture, and the amount of each substance in the mixture. Mixtures can be useful when something with many properties is desired.
Dissolving: Students learn that when a solid dissolves into a liquid, the solid is not gone, but rather is just mixed evenly through the liquid in such tiny pieces that it can’t be seen. They learn that dissolving is not the same as melting. Some solids, such as salt, dissolve completely in water, some, such as baking soda, dissolve partially, and some, such as sand, do not dissolve. Students learn that some properties of a solid- for example its flavor or odor- are still present after the solid has been dissolved. This is evidence that the solid has not gone away.
Design process: Students learn about ways in which scientists and engineers design new mixtures for specific purposes, using what they know about the properties of ingredients. They consider design goals- properties they want their mixture to have, test ingredients, decide on a mixture to test, make the mixture and record procedures, test the resulting mixture to see how well it matches the design goals, revise their recipes and continue testing. As students engage in the design process, they also learn important ideas about cause and effect.
