##
* *Reflection: Unit Exams
Forces and Acceleration Test - Section 1: Forces and Acceleration Test

The results for this assessment were mixed but averaged a 75% in most of my classes. I saw that students that struggled had a few different issues: lack of understanding of free body diagrams, inability to apply the mathematical model to all situations, and lack of understanding of the qualitative aspect of the mathematical model. For each of these struggles, I thought that I had built in supports, such as modeling in class, to help students. I also used backwards design so that students saw similar types of problems on worksheets and on the test. Unfortunately some of my students still struggled.

Next time I teach this unit I would make sure that students who struggle with free body diagrams in class receive one-on-one support or small group instruction to make sure they understand those concepts. I feel that some of the students who did not do well had trouble with free body diagrams in the previous unit, so I need to make sure that students understand those concepts before moving on to applying them.

*Applying models in a variety of situations*

*Unit Exams: Applying models in a variety of situations*

# Forces and Acceleration Test

Lesson 10 of 10

## Objective: Students will be able answer qualitative and quantitative questions about Newton's second law.

*70 minutes*

#### Forces and Acceleration Test

*70 min*

The goal of this lesson is for students to communicate what they have learned about Newton's Second Law through various types of questions and problems on a summative assessment. Students demonstrate their mastery the standard HS-PS2-1 which focuses on the relationships in Newton's second law. Students use the mathematical model that relate mass, net force and acceleration qualitatively and quantitatively to solve problems (SP2, SP5). In addition, by drawing free body diagrams, students create a visual representation of various situations to determine net force and use that information to find the mass or acceleration of an object. Many of the problems on the test mirror the activities done in class; scenarios on the test include: elevators, accelerating objects with friction & applied force, and a cart pulled along a track.

To complete the test, I have students work individually without talking to anyone. The Newton's second law equation is written on the board for students to use in addition to their calculator. I have students separate their desks and turn off their phones and flip them over on their desks so that they are not using any other resources besides what they have learned. As they complete the test I walk around a couple times to reduce cheating and to make sure that students are working through the problems. If students have questions, they raise their hand and I come to them to assist in any way that helps clarify what the question is asking without giving any hint to how to complete the problems.

The videos below show a few problems from the test and students' answers on each set of problems. The problems in the video below concern the qualitative relationships of Newton's second law. I chose to ask these as multiple choice questions to see what students understood when it came to how mass and force changes affected the acceleration of an object.

The following problem is an elevator situation where students are required to look at the net force vertically between weight and normal force. I chose to have students complete this problem showing their work to find the normal force because it required them to use the mathematical model for Newton's second law and how to find the net force.

The following problem requires students to apply what they know about free body diagrams and Newton's second law in one problem. They need to understand what forces are acting on the object and in which way as well as how to determine net force to use it in the Newton's second law equation.

*expand content*

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- LESSON 1: Modified Atwood Machine Lab
- LESSON 2: Determining and Using Newton's Second Law
- LESSON 3: Newton's Second Law and Free Body Diagrams, Part 1
- LESSON 4: Friction Lab, Day 1
- LESSON 5: Friction Lab, Day 2
- LESSON 6: Elevators and Newton's Second Law
- LESSON 7: Newton's Second Law and Free Body Diagrams, Part 2
- LESSON 8: Newton's Second Law with Groups
- LESSON 9: Newton's 2nd Law Review Day
- LESSON 10: Forces and Acceleration Test