Educational worksheet teaching gravity and friction concepts through illustrated examples for students to circle.

Problem Overview:

The task is to identify and circle the pictures that demonstrate gravity in red and those that demonstrate friction in blue. The worksheet provides definitions for both concepts:
- Gravity: A force that pulls objects down due to Earth's gravitational pull.
- Friction: A force that occurs when two things rub together.

Solution Approach:

We will analyze each picture to determine whether it illustrates gravity or friction, based on the provided definitions.

---

Picture Analysis:

#### Top Row:
1. Picture 1 (Tree with Falling Apples):
- Description: Apples are falling from a tree.
- Explanation: This demonstrates gravity because the apples are being pulled downward by Earth's gravitational force.
- Circle in: Red (gravity).

2. Picture 2 (Person Pushing a Box):
- Description: A person is pushing a box.
- Explanation: This does not directly show gravity but could involve friction if the box is sliding across a surface. However, the primary action here is pushing, which is unrelated to either concept.
- Circle in: Neither.

3. Picture 3 (Person Skiing):
- Description: A person is skiing on snow.
- Explanation: Skiing involves friction between the skis and the snow, as well as gravity pulling the person downhill.
- Circle in: Blue (friction) and Red (gravity).

#### Middle Row:
4. Picture 4 (Person Under a Car):
- Description: A person is under a car, and the car appears to be tipping over.
- Explanation: This demonstrates gravity because the car is being pulled downward by Earth's gravitational force.
- Circle in: Red (gravity).

5. Picture 5 (Person Eating Ice Cream):
- Description: A person is eating ice cream, and the ice cream is melting.
- Explanation: Melting ice cream is a thermal process and does not directly involve gravity or friction.
- Circle in: Neither.

6. Picture 6 (Person Ice Skating):
- Description: A person is ice skating.
- Explanation: Ice skating involves friction between the skates and the ice, as well as gravity keeping the person grounded.
- Circle in: Blue (friction) and Red (gravity).

#### Bottom Row:
7. Picture 7 (Person Jumping Off a Platform):
- Description: A person is jumping off a platform.
- Explanation: This demonstrates gravity because the person is being pulled downward by Earth's gravitational force after jumping.
- Circle in: Red (gravity).

8. Picture 8 (People Sliding Down a Slide):
- Description: People are sliding down a slide.
- Explanation: Sliding down a slide involves friction between the people and the slide, as well as gravity pulling them downward.
- Circle in: Blue (friction) and Red (gravity).

9. Picture 9 (Person Holding a Kite):
- Description: A person is holding a kite, and the kite is flying.
- Explanation: Flying a kite involves air resistance and tension in the string, but not directly gravity or friction.
- Circle in: Neither.

---

Final Answer:

- Red Circles (Gravity): Pictures 1, 3, 4, 7, 8
- Blue Circles (Friction): Pictures 3, 6, 8

Boxed Answer:
\[
\boxed{\text{Red: 1, 3, 4, 7, 8; Blue: 3, 6, 8}}
\]