Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 75 · 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.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the ironing time (b) how dark the writing is (c) the same paper (d) the kind of juice
2. 2.True or false: letting the paper dry is a job a child can do. (a) False (b) True
3. 3.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same cotton bud (b) how dark the writing is (c) the same paper (d) the iron setting
5. 5.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if cooled (c) yes, in the dark (d) yes, if shaken
6. 6.🧺 Which of these is not needed for the secret lemon message? (a) a balloon (b) lemon juice (c) a small bowl (d) white paper
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
8. 8.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) a battery cell (c) a cotton bud (d) a mirror
9. 9.True or false: plugging in the iron is a job a child can do. (a) True (b) False
10. 10.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) a battery cell (c) a small bowl (d) white paper
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) an adult with an iron (d) turmeric powder
13. 13.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) a mirror (c) a battery cell (d) white paper
14. 14.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) white paper (c) a magnet (d) a cotton bud
15. 15.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
16. 16.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
17. 17.⚖️ 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
18. 18.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) rub your eyes (c) lick your fingers (d) skip washing
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) lemon juice (c) white paper (d) a magnet
20. 20.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
21. 21.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) the youngest child (c) whoever is fastest (d) only an adult
22. 22.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
23. 23.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we keep it the same (b) we change it (c) we measure it
25. 25.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
26. 26.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
27. 27.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) blue (c) green (d) white
28. 28.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
29. 29.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) blue words (b) almost nothing (c) dark brown words (d) a rainbow
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) False (b) True
31. 31.True or false: yeast is not needed for the secret lemon message. (a) False (b) True
32. 32.True or false: white paper is needed for the secret lemon message. (a) False (b) True
33. 33.🔍 Which is the odd one out? (a) dipping the cotton bud (b) putting the iron away (c) writing the message (d) reading the message
34. 34.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we keep it the same (c) we change it
35. 35.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) lemon juice (c) white paper (d) a small bowl
36. 36.🧺 Which of these is needed for the secret lemon message? (a) a small bowl (b) a magnet (c) a balloon (d) a mirror
37. 37.True or false: turmeric powder is needed for the secret lemon message. (a) False (b) True
38. 38.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) cutting the lemon (c) plugging in the iron (d) dipping the cotton bud
39. 39.⚖️ 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
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) True (b) False

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