UNIT 5: Structure and Function of Organisms, Part 2
Explain
Teacher Note
Teacher Note
Dangerous metabolic by-products, such as hydrogen
peroxide, are also chemically changed into harmless
substances by
enzymes.
Teacher Note
Teacher Note
The diagram of the excretory system on RM 2
includes the heart as a location reference only.
Remind students that the heart is not part of the
excretory system.
Advance Preparation
Prepare a floor-size model of the digestive system:
Set up the classroom so the
middle of the room has two parallel pieces of masking tape down the length of the
room.
Depending on available space, the tapeline should be 2–4 feet apart.
Prepare a large ball of “food”
by
placing popcorn in 10 plastic sandwich bags.
Put
the popcorn-filled bags into a large plastic bag to make a “food ball.”
Teacher Instruction
Debrief the Explore activity.
Students should observe
that the gelatin area
liquefies when it comes in contact with the pineapple.
Read and discuss “Physical and Chemical Changes”
using the following activities
and facilitation questions.
Ask students to predict if swallowing food is impossible while standing on
your head.
Refer to the digestive system diagram and ask students how
food travels around all the curves in the digestive organs.
Provide time for students to observe
a demonstration of a marble being
squeezed down a large piece of aquarium tubing to simulate how
peristalsis squeezes food through the narrow tubelike esophagus.
Instruct students to model a “food ball”
pushed through the digestive tract
during peristalsis.
Ask students to stand on either side of the floor-size
model of the digestive system and move
the large plastic bag, keeping it
between the tape lines.
Instruct students to complete the science notebook entry,
relating the physical
and chemical changes that occur during digestion.
Review the science notebook entry with students.
Materials Materials
For teacher
small marble
50 cm of clear,
large aquarium
tubing
measuring tape
large trash bag
popcorn
10 sandwich-
size resealable
plastic bags
For each student
RM 1
RM 2
colored pencils
A
T
© REGION 4 EDUCA TION SERVICE CENTER.
ALL RIGHTS RESERVED.
Gateways to Science, STAAR Edition, Grade 7
Lesson 1: Physical and Chemical Changes in Digestion
UNIT 5: Structure and Function of Organisms, Part 2 RM 1
Digestive System
© REGION 4 EDUCA TION SERVICE CENTER.
ALL RIGHTS RESERVED.
Gateways to Science, STAAR Edition, Grade 7
Lesson 1: Physical and Chemical Changes in Digestion
UNIT 5: Structure and Function of Organisms, Part 2 RM 2
Excretory System
Lesson 1: Physical and Chemical Changes in Digestion
