Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 779 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.True or false: ironing the paper is a job for an adult. (a) True (b) False
2. 2.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) writing the message (c) dipping the cotton bud (d) reading the message
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a magnet (c) lemon juice (d) an adult with an iron
4. 4.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
5. 5.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) wash your hands (c) lick your fingers (d) skip washing
6. 6.True or false: letting the paper dry is a job for an adult. (a) False (b) True
7. 7.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) an adult with an iron (c) a magnet (d) a cotton bud
8. 8.🔍 Which is the odd one out? (a) letting the paper dry (b) cutting the lemon (c) writing the message (d) dipping the cotton bud
9. 9.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
10. 10.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
11. 11.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) lemon juice (c) a mirror (d) an adult with an iron
13. 13.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) cutting the lemon (c) dipping the cotton bud (d) writing the message
14. 14.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if cooled (c) yes, if shaken (d) yes, in the dark
15. 15.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) chemical (c) musical (d) magnetic
16. 16.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) white paper (c) a magnet (d) a balloon
17. 17.True or false: plugging in the iron is a job a child can do. (a) True (b) False
18. 18.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
19. 19.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) paper turns lemony (c) heat adds colour (d) the juice scorches first
20. 20.🔍 Which is the odd one out? (a) dipping the cotton bud (b) plugging in the iron (c) reading the message (d) writing the message
21. 21.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
22. 22.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) yeast (c) a battery cell (d) a cotton bud
23. 23.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) dipping the cotton bud (d) ironing the paper
24. 24.True or false: a magnet is needed for the secret lemon message. (a) True (b) False
25. 25.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) an adult with an iron (c) turmeric powder (d) a small bowl
26. 26.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
27. 27.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) an adult with an iron (c) lemon juice (d) a mirror
28. 28.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
29. 29.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) putting the iron away (d) letting the paper dry
30. 30.True or false: plugging in the iron is a job for an adult. (a) True (b) False
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we measure it (c) we keep it the same
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) the iron setting (c) the kind of juice (d) the same cotton bud
33. 33.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) white (c) brown (d) blue
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the same paper (c) the kind of juice
35. 35.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we change it (c) we keep it the same
37. 37.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the kind of juice (c) the same cotton bud
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) how dark the writing is (c) the same cotton bud (d) the same paper
40. 40.True or false: reading the message is a job a child can do. (a) True (b) False

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