There are many ways to submit assignments in Google Classroom.  Here are 3:

 

Method 1:  Screen Shots

1.  Open your lab report.  Take a screen shot of each page.

2.  Open the assignment on Google Classroom.

3.  Click Add Attachment.

4.  Select Add Photo and pick the photos of your lab from your Camera Roll.

5. Click Turn In.

 

Method 2:  From Docs Option 1

1.  Open your lab report.  Click the 3 dots in the right corner.

2.  Select Share and Export and then Send a Copy.

3.  Click on Classroom. (If you don't see it, click More and toggle Classroom to the right and click Done).

4.  Go into the assignment on Classroom and click on Turn In.

 

Method 3:  From Docs or Pages Option 2

1.  Open your report in Docs or Pages.

2.  Click on the 3 dots in the upper right corner.

3.  Click Share and Export, then Send a Copy.

4.  Save your file as a .pdf and choose to send to Drive.

5.  Go into Classroom and open the assignment.

6.  Click Add Attachment.

7.  Select From Drive and choose the new file you just copied.