Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 655 · 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.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) a rainbow (c) almost nothing (d) dark brown words
2. 2.True or false: reading the message is a job a child can do. (a) True (b) False
3. 3.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) ironing the paper (d) reading the message
4. 4.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
5. 5.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a small bowl (c) a mirror (d) a battery cell
6. 6.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) blue (c) green (d) brown
7. 7.⚖️ 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
8. 8.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a cotton bud (c) an adult with an iron (d) turmeric powder
9. 9.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a magnet (c) a cotton bud (d) a battery cell
10. 10.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
11. 11.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
12. 12.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) lick your fingers (c) rub your eyes (d) wash your hands
13. 13.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
14. 14.True or false: ironing the paper is a job a child can do. (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) how dark the writing is (b) the kind of juice (c) the ironing time
16. 16.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) an adult with an iron (c) lemon juice (d) a small bowl
18. 18.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if shaken (c) yes, if cooled (d) yes, in the dark
19. 19.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is magnetic (c) it can burn skin (d) it is cold
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) False (b) True
21. 21.⚖️ 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
22. 22.⚖️ 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) True (b) False
23. 23.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) physical (c) chemical (d) musical
24. 24.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) the paper ate it (c) dry juice is see-through (d) it turned into air
25. 25.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
26. 26.⚖️ 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
27. 27.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) an adult with an iron (c) a mirror (d) yeast
28. 28.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
29. 29.🛟 Who should use the hot iron in the secret message experiment? (a) only an adult (b) the youngest child (c) whoever is fastest (d) any child
30. 30.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
31. 31.🔍 Which is the odd one out? (a) plugging in the iron (b) cutting the lemon (c) putting the iron away (d) writing the message
32. 32.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we measure it (b) we change it (c) we keep it the same
34. 34.⚖️ 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
35. 35.⚖️ 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) False (b) True
36. 36.🧺 Do we need a small bowl for the secret lemon message? (a) not needed (b) needed
37. 37.⚖️ 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 iron setting (c) how dark the writing is (d) the same cotton bud
38. 38.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
39. 39.🍋 Which of these steps is a job a child can do? (a) writing the message (b) putting the iron away (c) plugging in the iron (d) ironing the paper
40. 40.🔍 Which is the odd one out? (a) putting the iron away (b) ironing the paper (c) dipping the cotton bud (d) cutting the lemon

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