Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 199 · 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: a magnet is not needed for the secret lemon message. (a) True (b) False
2. 2.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) how dark the writing is (b) the same paper (c) the kind of juice (d) the same cotton bud
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) False (b) True
4. 4.True or false: dipping the cotton bud is a job a child can do. (a) True (b) False
5. 5.🔍 Which is the odd one out? (a) cutting the lemon (b) letting the paper dry (c) ironing the paper (d) putting the iron away
6. 6.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the iron setting (b) the ironing time (c) the same cotton bud (d) the kind of juice
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we keep it the same (c) we change it
8. 8.⚖️ 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 keep it the same (c) we change it
9. 9.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) putting the iron away (c) dipping the cotton bud (d) writing the message
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a magnet (b) lemon juice (c) white paper (d) a cotton bud
11. 11.True or false: ironing the paper is a job for an adult. (a) True (b) False
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a cotton bud (c) yeast (d) a small bowl
13. 13.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) a small bowl (c) a balloon (d) yeast
14. 14.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a mirror (b) lemon juice (c) an adult with an iron (d) white paper
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we change it (c) we keep it the same
16. 16.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
17. 17.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) dark brown words (c) blue words (d) almost nothing
18. 18.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
19. 19.True or false: reading the message is a job for an adult. (a) True (b) False
20. 20.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) no, it stays brown (c) yes, if cooled (d) yes, in the dark
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we keep it the same (b) we measure it (c) we change it
22. 22.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) dipping the cotton bud (c) cutting the lemon (d) ironing the paper
23. 23.🍋 Which of these steps is a job for an adult? (a) cutting the lemon (b) dipping the cotton bud (c) writing the message (d) reading the message
24. 24.🛟 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
25. 25.True or false: writing the message is a job a child can do. (a) False (b) True
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) a balloon (d) an adult with an iron
27. 27.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
28. 28.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
29. 29.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) plugging in the iron (d) reading the message
30. 30.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
31. 31.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
32. 32.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) green (c) blue (d) white
33. 33.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is sticky (c) it is cold (d) it can burn skin
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) the same paper (c) how dark the writing is
35. 35.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
36. 36.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
37. 37.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
38. 38.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
39. 39.True or false: cutting the lemon is a job for an adult. (a) False (b) True
40. 40.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) yeast (c) turmeric powder (d) an adult with an iron

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