Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 855 · 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.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) reading the message (c) cutting the lemon (d) putting the iron away
2. 2.🔍 Which is the odd one out? (a) writing the message (b) dipping the cotton bud (c) putting the iron away (d) reading the message
3. 3.🧺 Which of these is needed for the secret lemon message? (a) an adult with an iron (b) a balloon (c) a magnet (d) turmeric powder
4. 4.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) putting the iron away (d) reading the message
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) True (b) False
6. 6.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
7. 7.True or false: putting the iron away is a job for an adult. (a) False (b) True
8. 8.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) skip washing (c) rub your eyes (d) lick your fingers
9. 9.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
10. 10.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) it gets darker (c) writing stays faint (d) the paper floats
11. 11.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) letting the paper dry (d) plugging in the iron
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the kind of juice (b) the same cotton bud (c) the same paper (d) how dark the writing is
13. 13.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
14. 14.True or false: an adult with an iron is not needed for the secret lemon message. (a) True (b) False
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same paper (b) how dark the writing is (c) the kind of juice
16. 16.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a cotton bud (c) lemon juice (d) a balloon
17. 17.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) lemon juice (c) a magnet (d) an adult with an iron
18. 18.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we measure it (c) we change it
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
21. 21.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) an adult with an iron (c) a cotton bud (d) a mirror
22. 22.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) letting the paper dry (d) cutting the lemon
23. 23.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) dark brown words (c) blue words (d) a rainbow
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
25. 25.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) white (c) brown (d) blue
26. 26.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
27. 27.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) yeast (c) white paper (d) turmeric powder
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
29. 29.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
30. 30.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
31. 31.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) lemon juice (c) a small bowl (d) a balloon
32. 32.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the kind of juice (b) the ironing time (c) how dark the writing is (d) the same cotton bud
34. 34.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) lemon juice (c) white paper (d) an adult with an iron
35. 35.⚖️ 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 keep it the same (c) we measure it
36. 36.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) magnetic (c) physical (d) musical
37. 37.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) plugging in the iron (d) letting the paper dry
38. 38.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we change it (c) we measure it
40. 40.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed

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