Act 1
1. Will the baby be a boy or girl?
2. Write down a guess.
Note: This lesson is based on a fun myth that a baby’s gender can be determined by their heart rate. Consider sharing with students that this isn’t scientifically accurate but instead a fun way for expecting parents to anticipate their new baby.
Act 2
3. What information would be useful to figure this out?
4. Write down some questions you have in your head right now.
Act 3
Sequel
5. Write an inequality to describe the conditions needed for a girl.
6. Write an inequality to describe the conditions needed for a boy.
7. What would happen if the baby had a heartbeat of exactly 140 beats per minute?
Common Core Standards
6.RP.A.3
Use ratio and rate reasoning to solve real-world and mathematical problems, e.g., by reasoning about tables of equivalent ratios, tape diagrams, double number line diagrams, or equations.
6.RP.A.3
Use ratio and rate reasoning to solve real-world and mathematical problems, e.g., by reasoning about tables of equivalent ratios, tape diagrams, double number line diagrams, or equations.
TEKS
6.4(H)
convert units within a measurement system, including the use of proportions and unit rates
6.4(H)
convert units within a measurement system, including the use of proportions and unit rates
When Math Happens 
Love your lessons overall this one should probably removed for scientific accuracy
https://www.healthline.com/health/pregnancy/baby-heart-rate-predicting-gender
Thank you for the comment! I added a disclaimer to make sure it’s more clear that this lesson is based on a fun myth.