Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 598 · 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.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
2. 2.🔮 Can the brown writing go back to being invisible? (a) yes, if cooled (b) no, it stays brown (c) yes, in the dark (d) yes, if shaken
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) False (b) True
4. 4.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
5. 5.🔍 Which is the odd one out? (a) reading the message (b) plugging in the iron (c) cutting the lemon (d) putting the iron away
6. 6.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) plugging in the iron (c) reading the message (d) writing the message
7. 7.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a mirror (d) a small bowl
9. 9.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) lemon juice (d) a balloon
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) False (b) True
11. 11.⚖️ 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 same cotton bud (c) how dark the writing is (d) the ironing time
12. 12.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
13. 13.True or false: reading the message is a job for an adult. (a) False (b) True
14. 14.⚖️ 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
15. 15.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) cutting the lemon (c) letting the paper dry (d) reading the message
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) how dark the writing is (b) the ironing time (c) the same paper (d) the kind of juice
17. 17.True or false: a battery cell is not needed for the secret lemon message. (a) True (b) False
18. 18.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) True (b) False
19. 19.True or false: lemon juice is needed for the secret lemon message. (a) True (b) False
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we keep it the same (c) we measure it
21. 21.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) dipping the cotton bud (c) plugging in the iron (d) ironing the paper
22. 22.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) white paper (c) turmeric powder (d) a cotton bud
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same cotton bud (b) the kind of juice (c) how dark the writing is
24. 24.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) False (b) True
26. 26.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) wash your hands (d) lick your fingers
27. 27.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) chemical (c) musical (d) physical
28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) a small bowl (d) a magnet
29. 29.🔍 Which is the odd one out? (a) putting the iron away (b) plugging in the iron (c) dipping the cotton bud (d) ironing the paper
30. 30.🍋 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) dipping the cotton bud
31. 31.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) lemon juice (c) a cotton bud (d) a battery cell
32. 32.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) an adult with an iron (c) a balloon (d) a mirror
33. 33.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) brown (c) white (d) blue
34. 34.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing turns green (c) writing stays faint (d) the paper floats
35. 35.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a battery cell (c) white paper (d) a small bowl
36. 36.🔍 Which is the odd one out? (a) reading the message (b) writing the message (c) cutting the lemon (d) dipping the cotton bud
37. 37.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
38. 38.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
39. 39.True or false: putting the iron away is a job a child can do. (a) True (b) False
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we keep it the same (c) we measure it

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