7.1.5 Gravity

Phenomenon – Measurement Tools

DAY 2 - EXPLORE MEASURING MASS and WEIGHT

Learning Objective: Scales are technology used to measure weight or mass.

Science & Engineering Practices: Using Mathematics and Computational Thinking

Obtaining, Evaluating, and Communicating Information

Crosscutting Concepts:Scale, Proportion and Quantity

Formative Assessment: Completion ofData table measuring 4 objects with 3 scales

Materials Needed:

1 spring scale per group of 3-6several “junk drawer” items which can hang

1 digital scale per group of 3-6and have a mass between 10 g and 500 g

1 triple beam balance per group of 3-6

1 Using Scales worksheet per student

Activities:A-Have students label the next available notebook page with today’s date.

B- Have students write down, “What kind of force is gravitation?” in their notebooks. Give a few

seconds to ponder then call on someone to answer. They should respond with at-a-distance force.

C- Have students write down, “When would gravity increase?” in their notebooks. Give a few seconds to ponder then call on someone to answer. They should respond with travel to a planet with larger mass.

D- Ask, “So how do we know that gravity changes? How do we measure gravity?” Allow some responses then click to reveal, “We use tools called scales.”

E- hand out the worksheet and have students complete the table as the types of scales are demonstrated.

F- Introduce a type of scale called a spring scale. Explain that it measures WEIGHT by detecting the force that pulls down on the little spring inside. Spring scales measure in Newtons. Guess where that unit got its name? Either demonstrate how to use the scale yourself, or click on the picture for a video tutorial.

G- Introduce a type of scale called a digital scale. Explain that it measures MASS by detecting the force that something exerts on the pan, then it takes away the force of gravity pulling the object down. Digital balances measure in grams (or milligrams, or kilograms, etc.) Either demonstrate how to use the scale yourself, or click on the picture for a video tutorial.

H- Introduce a type of scale called a triple beam balance. Explain that it measures MASS by comparing the amount that an object pushes down on one side of the balance to objects of known mass – the little sliders on the top. Triple beam balances measure in grams (or milligrams, or kilograms, etc.) Either demonstrate how to use the scale yourself, or click on the picture for a video tutorial.

I- Display the completed table so students may self-correct their answers.

J- Now allow students to practice using each of the types of scales 4 times. Each student should select a “junk drawer” item from the front table. (These should be items which can hang from the spring scale and measure between 10 g and 500 g mass.)

K- Each student should measure his/her object with all three scales (in any order.) Place as many scales as possible around the room and on group tables to speed the process up. Students should complete the data table as they go.

L- Once the first object has been measured using all three scales, have students return the object to the front table and select a new object to measure with all three scales.

M- Repeat until 4 objects have been measured by each student. (Note: this should be done individually – not as a group so that each student has a chance to practice.)

N- Have students think about other observations they made (i.e. the digital scale was much faster to use than the triple beam balance) and what other questions this activity generated.

O- Have students cut and tape worksheet into notebook.

P- Walk around the room awarding stamps to those who finish.

Student Worksheet

Record your observations as each of these scale types is demonstrated.

Property
Measured / Units / How does it work?
Spring Scale
Digital Scale
Triple Beam Balance

Collect data measurements on four different objects. Make sure to include units with each

measurement.

Object / Drawing / Spring Scale / Digital Scale / Triple Beam Balance
Different Scales
After completing the above activity, what other observations (not opinions) did you make? / What questions do you have?