Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 65 · 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 what we measure? (a) the same paper (b) the ironing time (c) how dark the writing is (d) the kind of juice
2. 2.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) an adult with an iron (c) white paper (d) a mirror
4. 4.🛟 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
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) True (b) False
6. 6.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a cotton bud (c) a magnet (d) a battery cell
7. 7.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) False (b) True
9. 9.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
10. 10.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a cotton bud (c) yeast (d) an adult with an iron
11. 11.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) putting the iron away (c) plugging in the iron (d) ironing the paper
12. 12.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
13. 13.True or false: letting the paper dry is a job a child can do. (a) False (b) True
14. 14.True or false: white paper is not needed for the secret lemon message. (a) True (b) False
15. 15.🍋 Which of these steps is a job a child can do? (a) letting the paper dry (b) plugging in the iron (c) cutting the lemon (d) ironing the paper
16. 16.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
17. 17.🛟 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
18. 18.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) almost nothing (c) blue words (d) dark brown words
19. 19.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
20. 20.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it is magnetic (d) it can burn skin
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is what we measure. (a) True (b) False
22. 22.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) musical (c) magnetic (d) physical
23. 23.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) white (c) green (d) blue
24. 24.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
25. 25.⚖️ 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
26. 26.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) writing the message (c) cutting the lemon (d) putting the iron away
27. 27.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) turmeric powder (c) a cotton bud (d) lemon juice
28. 28.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, in the dark (c) yes, if cooled (d) yes, if shaken
29. 29.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) an adult with an iron (c) a battery cell (d) a cotton bud
30. 30.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
31. 31.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) an adult with an iron (b) white paper (c) yeast (d) a cotton bud
32. 32.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) turmeric powder (c) a cotton bud (d) a small bowl
33. 33.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
34. 34.🍋 Which of these steps is a job for an adult? (a) writing the message (b) letting the paper dry (c) dipping the cotton bud (d) ironing the paper
35. 35.⚖️ 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
36. 36.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) turmeric powder (c) yeast (d) an adult with an iron
37. 37.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) lemon juice (c) a battery cell (d) turmeric powder
38. 38.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
39. 39.🔍 Which is the odd one out? (a) plugging in the iron (b) ironing the paper (c) putting the iron away (d) reading the message
40. 40.⚖️ 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) how dark the writing is (d) the kind of juice

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