Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 477 · 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 a balloon for the secret lemon message? (a) not needed (b) needed
2. 2.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) green (c) white (d) brown
3. 3.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
4. 4.True or false: cutting the lemon is a job for an adult. (a) False (b) True
5. 5.🧺 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 magnet (d) a cotton bud
6. 6.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
7. 7.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) wash your hands (d) lick your fingers
8. 8.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) whoever is fastest (c) only an adult (d) the youngest child
9. 9.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a magnet (c) turmeric powder (d) a cotton bud
10. 10.🔍 Which is the odd one out? (a) letting the paper dry (b) reading the message (c) writing the message (d) cutting the lemon
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) True (b) False
12. 12.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
13. 13.⚖️ 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 cotton bud (c) the same paper (d) the kind of juice
14. 14.True or false: putting the iron away is a job for an adult. (a) False (b) True
15. 15.🔍 Which is the odd one out? (a) writing the message (b) putting the iron away (c) plugging in the iron (d) ironing the paper
16. 16.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
17. 17.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) no, it stays brown (d) yes, if cooled
18. 18.True or false: writing the message is a job a child can do. (a) False (b) True
19. 19.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) a small bowl (c) turmeric powder (d) lemon juice
20. 20.🍋 Secret message: who does this step — plugging in the iron? (a) a child can do it (b) an adult does it
21. 21.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) the paper floats (c) writing stays faint (d) it gets darker
22. 22.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a small bowl (c) a cotton bud (d) a mirror
23. 23.⚖️ 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 keep it the same (c) we measure it
24. 24.True or false: ironing the paper is a job a child can do. (a) True (b) False
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) True (b) False
26. 26.True or false: plugging in the iron is a job a child can do. (a) True (b) False
27. 27.🧺 Which of these is not needed for the secret lemon message? (a) a battery cell (b) lemon juice (c) white paper (d) an adult with an iron
28. 28.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
29. 29.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
30. 30.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
31. 31.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is sticky (c) it is magnetic (d) it can burn skin
32. 32.🍋 Which of these steps is a job for an adult? (a) reading the message (b) writing the message (c) dipping the cotton bud (d) plugging in the iron
33. 33.⚖️ 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 ironing time
34. 34.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
35. 35.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
36. 36.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
37. 37.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
38. 38.⚖️ 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 cotton bud
39. 39.True or false: a battery cell is needed for the secret lemon message. (a) False (b) True
40. 40.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) letting the paper dry (d) cutting the lemon

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