Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 351 · 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.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
2. 2.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) it gets darker (d) writing stays faint
3. 3.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
4. 4.🍋 Which of these steps is a job for an adult? (a) writing the message (b) cutting the lemon (c) letting the paper dry (d) dipping the cotton bud
5. 5.🔍 Which is the odd one out? (a) ironing the paper (b) cutting the lemon (c) putting the iron away (d) letting the paper dry
6. 6.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
7. 7.🔍 Which is the odd one out? (a) plugging in the iron (b) putting the iron away (c) ironing the paper (d) writing the message
8. 8.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
9. 9.🍋 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) writing the message
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) the same paper (c) the ironing time (d) the kind of juice
11. 11.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
12. 12.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is cold (c) it is sticky (d) it can burn skin
13. 13.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) the youngest child (c) any child (d) whoever is fastest
14. 14.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
15. 15.True or false: reading the message is a job a child can do. (a) False (b) True
16. 16.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) lemon juice (c) turmeric powder (d) a magnet
17. 17.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) plugging in the iron (d) dipping the cotton bud
18. 18.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) skip washing (d) wash your hands
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) a small bowl (c) white paper (d) lemon juice
20. 20.⚖️ 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
21. 21.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, in the dark (c) yes, if shaken (d) yes, if cooled
22. 22.True or false: ironing the paper is a job for an adult. (a) True (b) False
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we change it (b) we measure it (c) we keep it the same
24. 24.⚖️ 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 measure it (c) we keep it the same
25. 25.⚖️ 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
26. 26.🧺 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 balloon
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) True (b) False
28. 28.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) brown (c) green (d) blue
29. 29.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
30. 30.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
31. 31.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) physical (c) musical (d) chemical
32. 32.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) white paper (c) a balloon (d) lemon juice
33. 33.🔍 Which is the odd one out? (a) dipping the cotton bud (b) plugging in the iron (c) reading the message (d) writing the message
34. 34.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a battery cell (c) a small bowl (d) a mirror
35. 35.🔍 Which is the odd one out? (a) putting the iron away (b) plugging in the iron (c) cutting the lemon (d) dipping the cotton bud
36. 36.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
37. 37.True or false: white paper is needed for the secret lemon message. (a) False (b) True
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the ironing time (b) the kind of juice (c) how dark the writing is
39. 39.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) turmeric powder (c) an adult with an iron (d) lemon juice
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) white paper (c) an adult with an iron (d) lemon juice

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