Lesson: Mac ’n’ Cheese, Please!

Discuss how ingredients may change during food preparation.

• Ask: What are some of your favorite foods? Let students share. Ask: What ingredients are used, and how is the food prepared? What changes happen to the ingredients during preparation? What do you think causes those changes? 
• Ask students if they think any of the changes, like baking a pizza or making a salad, can be undone.. Discuss their ideas.

Watch a video about reversible and irreversible changes in cooking.

• Make a table with these four foods in the rows: water, chocolate, egg, and bread dough. Add a column for each of these two questions: Will it change when you add heat? Will it change back when you remove the heat? Ask students and tally their predictions.
• Play the video “Cooking Science!” Then revisit the chart. Add a third column for “Reversible or Not?” Ask students where you could write “reversible” (for water and chocolate) and where you could write “not” (for egg and bread dough). Discuss whether students’ predictions in the first two columns were supported with evidence from the video.

Read an article about the history and science of mac ’n’ cheese.

• Preview the article. Then read the article as a class. Discuss the different societal needs that macaroni and cheese addressed (e.g., affordable food that lasts a long time) and how changing the basic ingredients made it possible (e.g., adding emulsifiers to the cheese or drying out the cheese). Reinforce important information with the Quick Quiz.
• Distribute the Word Decoder vocabulary skills sheet. Allow students to complete it in pairs, then review it as a class. 

Demonstrate understanding with a summary of how boxed macaroni and cheese becomes a meal.

• Revisiting the graphic “From Box to Meal” (p. 9), ask students what changes turn boxed macaroni and cheese into a meal. Have them write or draw their responses and note how the ingredients change from the boxed version to the cooked version. (You boil water to cook the pasta. Then you drain the water and stir in cheese powder, milk, and butter. The cooked pasta becomes soft from cooking in the boiling water. The cheese powder becomes gooey and liquid-like when it’s heated with milk and butter. The ingredients have been changed into something new that can’t be changed back. The change is irreversible. You may want to note that even if you cook pasta and let it dry out, it would be different on the inside than before you cooked it.)

Analyze a graph about melting points.

• Preview the Melting Measurements graph skills sheet. Allow students to complete in pairs and discuss the answers as a class. Discuss melting again as an irreversible or reversible change.

⇨ Learning Extension: Use the library or internet to research your favorite food. Then create your own article about the history and science of that food. Remember to add photos, graphs, and other visual elements.