Invisible Ink Experiment Worksheet

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

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