Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 638 · 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.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) rub your eyes (c) skip washing (d) lick your fingers
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) an adult with an iron (c) a cotton bud (d) a balloon
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) the kind of juice (c) how dark the writing is (d) the iron setting
4. 4.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) white paper (c) a balloon (d) a mirror
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we keep it the same (c) we change it
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) turmeric powder (c) a small bowl (d) a cotton bud
7. 7.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is magnetic (c) it is sticky (d) it can burn skin
8. 8.🔍 Which is the odd one out? (a) plugging in the iron (b) letting the paper dry (c) cutting the lemon (d) ironing the paper
9. 9.True or false: ironing the paper is a job a child can do. (a) True (b) False
10. 10.🛟 Who should use the hot iron in the secret message experiment? (a) the youngest child (b) any child (c) whoever is fastest (d) only an adult
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
12. 12.⚖️ 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
13. 13.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
14. 14.🔍 Which is the odd one out? (a) reading the message (b) dipping the cotton bud (c) writing the message (d) putting the iron away
15. 15.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
16. 16.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
17. 17.⚖️ 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
18. 18.⚖️ 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 same cotton bud (c) the kind of juice (d) the same paper
19. 19.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
20. 20.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) True (b) False
21. 21.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
22. 22.🔍 Which is the odd one out? (a) letting the paper dry (b) plugging in the iron (c) dipping the cotton bud (d) writing the message
23. 23.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
24. 24.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
25. 25.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) lemon juice (c) a battery cell (d) turmeric powder
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is the one thing we change. (a) True (b) False
27. 27.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a small bowl (c) a battery cell (d) a mirror
28. 28.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) a cotton bud (d) a mirror
29. 29.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) brown (d) white
30. 30.True or false: letting the paper dry is a job a child can do. (a) True (b) False
31. 31.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) yes, if cooled (d) no, it stays brown
32. 32.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) False (b) True
33. 33.True or false: a balloon is needed for the secret lemon message. (a) False (b) True
34. 34.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) a small bowl (d) yeast
35. 35.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) putting the iron away (d) letting the paper dry
36. 36.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
37. 37.🔍 Which is the odd one out? (a) dipping the cotton bud (b) cutting the lemon (c) plugging in the iron (d) putting the iron away
38. 38.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) dark brown words (b) almost nothing (c) a rainbow (d) blue words
39. 39.🧺 Which of these is not needed for the secret lemon message? (a) a mirror (b) lemon juice (c) a cotton bud (d) a small bowl
40. 40.⚖️ 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 same cotton bud (c) the kind of juice

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